[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
# RUN: llc -run-pass x86-flags-copy-lowering -verify-machineinstrs -o - %s | FileCheck %s
|
|
|
|
|
#
|
|
|
|
|
# Lower various interesting copy patterns of EFLAGS without using LAHF/SAHF.
|
|
|
|
|
|
|
|
|
|
--- |
|
|
|
|
|
target triple = "x86_64-unknown-unknown"
|
|
|
|
|
|
|
|
|
|
declare void @foo()
|
|
|
|
|
|
|
|
|
|
define i32 @test_branch(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret i32 0
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define i32 @test_branch_fallthrough(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret i32 0
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_setcc(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_cmov(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_adc(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_sbb(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_adcx(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_adox(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_rcl(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
define void @test_rcr(i64 %a, i64 %b) {
|
|
|
|
|
entry:
|
|
|
|
|
call void @foo()
|
|
|
|
|
ret void
|
|
|
|
|
}
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_branch
|
|
|
|
|
# CHECK-LABEL: name: test_branch
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
successors: %bb.1, %bb.2, %bb.3
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
CMP64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%2:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[A_REG:[^:]*]]:gr8 = SETAr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[B_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %2
|
|
|
|
|
JA_1 %bb.1, implicit $eflags
|
|
|
|
|
JB_1 %bb.2, implicit $eflags
|
|
|
|
|
JMP_1 %bb.3
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
;
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK: TEST8rr %[[A_REG]], %[[A_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: JNE_1 %bb.1, implicit killed $eflags
|
|
|
|
|
; CHECK-SAME: {{$[[:space:]]}}
|
|
|
|
|
; CHECK-NEXT: bb.4:
|
|
|
|
|
; CHECK-NEXT: successors: {{.*$}}
|
|
|
|
|
; CHECK-SAME: {{$[[:space:]]}}
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK-NEXT: TEST8rr %[[B_REG]], %[[B_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: JNE_1 %bb.2, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: JMP_1 %bb.3
|
|
|
|
|
|
|
|
|
|
bb.1:
|
|
|
|
|
%3:gr32 = MOV32ri64 42
|
|
|
|
|
$eax = COPY %3
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
bb.2:
|
|
|
|
|
%4:gr32 = MOV32ri64 43
|
|
|
|
|
$eax = COPY %4
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
bb.3:
|
|
|
|
|
%5:gr32 = MOV32r0 implicit-def dead $eflags
|
|
|
|
|
$eax = COPY %5
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_branch_fallthrough
|
|
|
|
|
# CHECK-LABEL: name: test_branch_fallthrough
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
successors: %bb.1, %bb.2, %bb.3
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
CMP64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%2:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[A_REG:[^:]*]]:gr8 = SETAr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[B_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %2
|
|
|
|
|
JA_1 %bb.2, implicit $eflags
|
|
|
|
|
JB_1 %bb.3, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
;
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK: TEST8rr %[[A_REG]], %[[A_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: JNE_1 %bb.2, implicit killed $eflags
|
|
|
|
|
; CHECK-SAME: {{$[[:space:]]}}
|
|
|
|
|
; CHECK-NEXT: bb.4:
|
|
|
|
|
; CHECK-NEXT: successors: {{.*$}}
|
|
|
|
|
; CHECK-SAME: {{$[[:space:]]}}
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK-NEXT: TEST8rr %[[B_REG]], %[[B_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: JNE_1 %bb.3, implicit killed $eflags
|
|
|
|
|
; CHECK-SAME: {{$[[:space:]]}}
|
|
|
|
|
; CHECK-NEXT: bb.1:
|
|
|
|
|
|
|
|
|
|
bb.1:
|
|
|
|
|
%5:gr32 = MOV32r0 implicit-def dead $eflags
|
|
|
|
|
$eax = COPY %5
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
bb.2:
|
|
|
|
|
%3:gr32 = MOV32ri64 42
|
|
|
|
|
$eax = COPY %3
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
bb.3:
|
|
|
|
|
%4:gr32 = MOV32ri64 43
|
|
|
|
|
$eax = COPY %4
|
|
|
|
|
RET 0, $eax
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_setcc
|
|
|
|
|
# CHECK-LABEL: name: test_setcc
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
CMP64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%2:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[A_REG:[^:]*]]:gr8 = SETAr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[B_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[E_REG:[^:]*]]:gr8 = SETEr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[NE_REG:[^:]*]]:gr8 = SETNEr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %2
|
|
|
|
|
%3:gr8 = SETAr implicit $eflags
|
|
|
|
|
%4:gr8 = SETBr implicit $eflags
|
|
|
|
|
%5:gr8 = SETEr implicit $eflags
|
2018-04-11 09:09:10 +08:00
|
|
|
SETNEm $rsp, 1, $noreg, -16, $noreg, implicit killed $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
MOV8mr $rsp, 1, $noreg, -16, $noreg, killed %3
|
|
|
|
|
MOV8mr $rsp, 1, $noreg, -16, $noreg, killed %4
|
|
|
|
|
MOV8mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
; CHECK-NOT: = SET{{.*}}
|
|
|
|
|
; CHECK: MOV8mr {{.*}}, killed %[[A_REG]]
|
|
|
|
|
; CHECK-CHECK: MOV8mr {{.*}}, killed %[[B_REG]]
|
|
|
|
|
; CHECK-CHECK: MOV8mr {{.*}}, killed %[[E_REG]]
|
|
|
|
|
; CHECK-CHECK: MOV8mr {{.*}}, killed %[[NE_REG]]
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_cmov
|
|
|
|
|
# CHECK-LABEL: name: test_cmov
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
CMP64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%2:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[A_REG:[^:]*]]:gr8 = SETAr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[B_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[E_REG:[^:]*]]:gr8 = SETEr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %2
|
|
|
|
|
%3:gr64 = CMOVA64rr %0, %1, implicit $eflags
|
|
|
|
|
%4:gr64 = CMOVB64rr %0, %1, implicit $eflags
|
|
|
|
|
%5:gr64 = CMOVE64rr %0, %1, implicit $eflags
|
|
|
|
|
%6:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK: TEST8rr %[[A_REG]], %[[A_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %3:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK-NEXT: TEST8rr %[[B_REG]], %[[B_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %4:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK-NEXT: TEST8rr %[[E_REG]], %[[E_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %5:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK-NEXT: TEST8rr %[[E_REG]], %[[E_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %6:gr64 = CMOVE64rr %0, %1, implicit killed $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %3
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %4
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %6
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_adc
|
|
|
|
|
# CHECK-LABEL: name: test_adc
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = ADD64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[CF_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = ADC64ri32 %2:gr64, 42, implicit-def $eflags, implicit $eflags
|
|
|
|
|
%5:gr64 = ADC64ri32 %4:gr64, 42, implicit-def $eflags, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
; CHECK: dead %{{[^:]*}}:gr8 = ADD8ri %[[CF_REG]], 255, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %4:gr64 = ADC64ri32 %2, 42, implicit-def $eflags, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = ADC64ri32 %4, 42, implicit-def{{( dead)?}} $eflags, implicit{{( killed)?}} $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_sbb
|
|
|
|
|
# CHECK-LABEL: name: test_sbb
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = SUB64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY killed $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[CF_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = SBB64ri32 %2:gr64, 42, implicit-def $eflags, implicit killed $eflags
|
|
|
|
|
%5:gr64 = SBB64ri32 %4:gr64, 42, implicit-def dead $eflags, implicit killed $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
; CHECK: dead %{{[^:]*}}:gr8 = ADD8ri %[[CF_REG]], 255, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %4:gr64 = SBB64ri32 %2, 42, implicit-def $eflags, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = SBB64ri32 %4, 42, implicit-def{{( dead)?}} $eflags, implicit{{( killed)?}} $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_adcx
|
|
|
|
|
# CHECK-LABEL: name: test_adcx
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = ADD64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[E_REG:[^:]*]]:gr8 = SETEr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[CF_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = CMOVE64rr %0, %1, implicit $eflags
|
|
|
|
|
%5:gr64 = MOV64ri32 42
|
|
|
|
|
%6:gr64 = ADCX64rr %2, %5, implicit-def $eflags, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK: TEST8rr %[[E_REG]], %[[E_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %4:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = MOV64ri32 42
|
|
|
|
|
; CHECK-NEXT: dead %{{[^:]*}}:gr8 = ADD8ri %[[CF_REG]], 255, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %6:gr64 = ADCX64rr %2, %5, implicit-def{{( dead)?}} $eflags, implicit killed $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %4
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %6
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_adox
|
|
|
|
|
# CHECK-LABEL: name: test_adox
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = ADD64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[E_REG:[^:]*]]:gr8 = SETEr implicit $eflags
|
|
|
|
|
; CHECK-NEXT: %[[OF_REG:[^:]*]]:gr8 = SETOr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = CMOVE64rr %0, %1, implicit $eflags
|
|
|
|
|
%5:gr64 = MOV64ri32 42
|
|
|
|
|
%6:gr64 = ADOX64rr %2, %5, implicit-def $eflags, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
2018-04-18 23:52:50 +08:00
|
|
|
; CHECK: TEST8rr %[[E_REG]], %[[E_REG]], implicit-def $eflags
|
[x86] Introduce a pass to begin more systematically fixing PR36028 and similar issues.
The key idea is to lower COPY nodes populating EFLAGS by scanning the
uses of EFLAGS and introducing dedicated code to preserve the necessary
state in a GPR. In the vast majority of cases, these uses are cmovCC and
jCC instructions. For such cases, we can very easily save and restore
the necessary information by simply inserting a setCC into a GPR where
the original flags are live, and then testing that GPR directly to feed
the cmov or conditional branch.
However, things are a bit more tricky if arithmetic is using the flags.
This patch handles the vast majority of cases that seem to come up in
practice: adc, adcx, adox, rcl, and rcr; all without taking advantage of
partially preserved EFLAGS as LLVM doesn't currently model that at all.
There are a large number of operations that techinaclly observe EFLAGS
currently but shouldn't in this case -- they typically are using DF.
Currently, they will not be handled by this approach. However, I have
never seen this issue come up in practice. It is already pretty rare to
have these patterns come up in practical code with LLVM. I had to resort
to writing MIR tests to cover most of the logic in this pass already.
I suspect even with its current amount of coverage of arithmetic users
of EFLAGS it will be a significant improvement over the current use of
pushf/popf. It will also produce substantially faster code in most of
the common patterns.
This patch also removes all of the old lowering for EFLAGS copies, and
the hack that forced us to use a frame pointer when EFLAGS copies were
found anywhere in a function so that the dynamic stack adjustment wasn't
a problem. None of this is needed as we now lower all of these copies
directly in MI and without require stack adjustments.
Lots of thanks to Reid who came up with several aspects of this
approach, and Craig who helped me work out a couple of things tripping
me up while working on this.
Differential Revision: https://reviews.llvm.org/D45146
llvm-svn: 329657
2018-04-10 09:41:17 +08:00
|
|
|
; CHECK-NEXT: %4:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = MOV64ri32 42
|
|
|
|
|
; CHECK-NEXT: dead %{{[^:]*}}:gr8 = ADD8ri %[[OF_REG]], 127, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %6:gr64 = ADOX64rr %2, %5, implicit-def{{( dead)?}} $eflags, implicit killed $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %4
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %6
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_rcl
|
|
|
|
|
# CHECK-LABEL: name: test_rcl
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = ADD64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[CF_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = RCL64r1 %2:gr64, implicit-def $eflags, implicit $eflags
|
|
|
|
|
%5:gr64 = RCL64r1 %4:gr64, implicit-def $eflags, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
; CHECK: dead %{{[^:]*}}:gr8 = ADD8ri %[[CF_REG]], 255, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %4:gr64 = RCL64r1 %2, implicit-def $eflags, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = RCL64r1 %4, implicit-def{{( dead)?}} $eflags, implicit{{( killed)?}} $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|
|
|
|
|
---
|
|
|
|
|
name: test_rcr
|
|
|
|
|
# CHECK-LABEL: name: test_rcr
|
|
|
|
|
liveins:
|
|
|
|
|
- { reg: '$rdi', virtual-reg: '%0' }
|
|
|
|
|
- { reg: '$rsi', virtual-reg: '%1' }
|
|
|
|
|
body: |
|
|
|
|
|
bb.0:
|
|
|
|
|
liveins: $rdi, $rsi
|
|
|
|
|
|
|
|
|
|
%0:gr64 = COPY $rdi
|
|
|
|
|
%1:gr64 = COPY $rsi
|
|
|
|
|
%2:gr64 = ADD64rr %0, %1, implicit-def $eflags
|
|
|
|
|
%3:gr64 = COPY $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
; CHECK: %[[CF_REG:[^:]*]]:gr8 = SETBr implicit $eflags
|
|
|
|
|
; CHECK-NOT: COPY{{( killed)?}} $eflags
|
|
|
|
|
|
|
|
|
|
ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
|
|
|
|
|
ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
|
|
|
|
|
|
|
|
|
|
$eflags = COPY %3
|
|
|
|
|
%4:gr64 = RCR64r1 %2:gr64, implicit-def $eflags, implicit $eflags
|
|
|
|
|
%5:gr64 = RCR64r1 %4:gr64, implicit-def $eflags, implicit $eflags
|
|
|
|
|
; CHECK-NOT: $eflags =
|
|
|
|
|
; CHECK: dead %{{[^:]*}}:gr8 = ADD8ri %[[CF_REG]], 255, implicit-def $eflags
|
|
|
|
|
; CHECK-NEXT: %4:gr64 = RCR64r1 %2, implicit-def $eflags, implicit killed $eflags
|
|
|
|
|
; CHECK-NEXT: %5:gr64 = RCR64r1 %4, implicit-def{{( dead)?}} $eflags, implicit{{( killed)?}} $eflags
|
|
|
|
|
MOV64mr $rsp, 1, $noreg, -16, $noreg, killed %5
|
|
|
|
|
|
|
|
|
|
RET 0
|
|
|
|
|
|
|
|
|
|
...
|