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llvm-project/llvm/test/CodeGen/AArch64/machine-copy-remove.ll

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[AArch64] Add pass to remove redundant copy after RA Summary: This change will add a pass to remove unnecessary zero copies in target blocks of cbz/cbnz instructions. E.g., the copy instruction in the code below can be removed because the cbz jumps to BB1 when x0 is zero : BB0: cbz x0, .BB1 BB1: mov x0, xzr Jun Reviewers: gberry, jmolloy, HaoLiu, MatzeB, mcrosier Subscribers: mcrosier, mssimpso, haicheng, bmakam, llvm-commits, aemerson, rengolin Differential Revision: http://reviews.llvm.org/D16203 llvm-svn: 261004
2016-02-17 04:02:39 +08:00
; RUN: llc -mtriple=aarch64-linux-gnu -mcpu=cortex-a57 -verify-machineinstrs < %s | FileCheck %s
AArch64: improve redundant copy elimination. Mostly, this fixes the bug that if the CBZ guaranteed Xn but Wn was used, we didn't sort out the use-def chain properly. I've also made it check more than just the last instruction for a compatible CBZ (so it can cope without fallthroughs). I'd have liked to do that separately, but it's helps writing the test. Finally, I removed some custom loops in favour of MachineInstr helpers and refactored the control flow to flatten it and avoid possibly quadratic iterations in blocks with many copies. NFC for these, just a general tidy-up. llvm-svn: 261154
2016-02-18 05:16:53 +08:00
; CHECK-LABEL: f_XX:
[AArch64] Add pass to remove redundant copy after RA Summary: This change will add a pass to remove unnecessary zero copies in target blocks of cbz/cbnz instructions. E.g., the copy instruction in the code below can be removed because the cbz jumps to BB1 when x0 is zero : BB0: cbz x0, .BB1 BB1: mov x0, xzr Jun Reviewers: gberry, jmolloy, HaoLiu, MatzeB, mcrosier Subscribers: mcrosier, mssimpso, haicheng, bmakam, llvm-commits, aemerson, rengolin Differential Revision: http://reviews.llvm.org/D16203 llvm-svn: 261004
2016-02-17 04:02:39 +08:00
; CHECK: cbz x[[REG:[0-9]+]], [[BB:.LBB.*]]
; CHECK: [[BB]]:
; CHECK-NOT: mov x[[REG]], xzr
define i64 @f_XX(i64 %n, i64* nocapture readonly %P) {
entry:
%tobool = icmp eq i64 %n, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
%0 = load i64, i64* %P
br label %if.end
if.end: ; preds = %entry, %if.then
%a.0 = phi i64 [ %0, %if.then ], [ 0, %entry ]
ret i64 %a.0
}
AArch64: improve redundant copy elimination. Mostly, this fixes the bug that if the CBZ guaranteed Xn but Wn was used, we didn't sort out the use-def chain properly. I've also made it check more than just the last instruction for a compatible CBZ (so it can cope without fallthroughs). I'd have liked to do that separately, but it's helps writing the test. Finally, I removed some custom loops in favour of MachineInstr helpers and refactored the control flow to flatten it and avoid possibly quadratic iterations in blocks with many copies. NFC for these, just a general tidy-up. llvm-svn: 261154
2016-02-18 05:16:53 +08:00
; CHECK-LABEL: f_WW:
[AArch64] Add pass to remove redundant copy after RA Summary: This change will add a pass to remove unnecessary zero copies in target blocks of cbz/cbnz instructions. E.g., the copy instruction in the code below can be removed because the cbz jumps to BB1 when x0 is zero : BB0: cbz x0, .BB1 BB1: mov x0, xzr Jun Reviewers: gberry, jmolloy, HaoLiu, MatzeB, mcrosier Subscribers: mcrosier, mssimpso, haicheng, bmakam, llvm-commits, aemerson, rengolin Differential Revision: http://reviews.llvm.org/D16203 llvm-svn: 261004
2016-02-17 04:02:39 +08:00
; CHECK: cbz w[[REG:[0-9]+]], [[BB:.LBB.*]]
; CHECK: [[BB]]:
; CHECK-NOT: mov w[[REG]], wzr
define i32 @f_WW(i32 %n, i32* nocapture readonly %P) {
entry:
%tobool = icmp eq i32 %n, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
%0 = load i32, i32* %P
br label %if.end
if.end: ; preds = %entry, %if.then
%a.0 = phi i32 [ %0, %if.then ], [ 0, %entry ]
ret i32 %a.0
}
AArch64: improve redundant copy elimination. Mostly, this fixes the bug that if the CBZ guaranteed Xn but Wn was used, we didn't sort out the use-def chain properly. I've also made it check more than just the last instruction for a compatible CBZ (so it can cope without fallthroughs). I'd have liked to do that separately, but it's helps writing the test. Finally, I removed some custom loops in favour of MachineInstr helpers and refactored the control flow to flatten it and avoid possibly quadratic iterations in blocks with many copies. NFC for these, just a general tidy-up. llvm-svn: 261154
2016-02-18 05:16:53 +08:00
; CHECK-LABEL: f_XW:
[AArch64] Add pass to remove redundant copy after RA Summary: This change will add a pass to remove unnecessary zero copies in target blocks of cbz/cbnz instructions. E.g., the copy instruction in the code below can be removed because the cbz jumps to BB1 when x0 is zero : BB0: cbz x0, .BB1 BB1: mov x0, xzr Jun Reviewers: gberry, jmolloy, HaoLiu, MatzeB, mcrosier Subscribers: mcrosier, mssimpso, haicheng, bmakam, llvm-commits, aemerson, rengolin Differential Revision: http://reviews.llvm.org/D16203 llvm-svn: 261004
2016-02-17 04:02:39 +08:00
; CHECK: cbz x[[REG:[0-9]+]], [[BB:.LBB.*]]
; CHECK: [[BB]]:
; CHECK-NOT: mov w[[REG]], wzr
define i32 @f_XW(i64 %n, i32* nocapture readonly %P) {
entry:
%tobool = icmp eq i64 %n, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
%0 = load i32, i32* %P
br label %if.end
if.end: ; preds = %entry, %if.then
%a.0 = phi i32 [ %0, %if.then ], [ 0, %entry ]
ret i32 %a.0
}
AArch64: improve redundant copy elimination. Mostly, this fixes the bug that if the CBZ guaranteed Xn but Wn was used, we didn't sort out the use-def chain properly. I've also made it check more than just the last instruction for a compatible CBZ (so it can cope without fallthroughs). I'd have liked to do that separately, but it's helps writing the test. Finally, I removed some custom loops in favour of MachineInstr helpers and refactored the control flow to flatten it and avoid possibly quadratic iterations in blocks with many copies. NFC for these, just a general tidy-up. llvm-svn: 261154
2016-02-18 05:16:53 +08:00
; CHECK-LABEL: f_WX:
[AArch64] Add pass to remove redundant copy after RA Summary: This change will add a pass to remove unnecessary zero copies in target blocks of cbz/cbnz instructions. E.g., the copy instruction in the code below can be removed because the cbz jumps to BB1 when x0 is zero : BB0: cbz x0, .BB1 BB1: mov x0, xzr Jun Reviewers: gberry, jmolloy, HaoLiu, MatzeB, mcrosier Subscribers: mcrosier, mssimpso, haicheng, bmakam, llvm-commits, aemerson, rengolin Differential Revision: http://reviews.llvm.org/D16203 llvm-svn: 261004
2016-02-17 04:02:39 +08:00
; CHECK: cbz w[[REG:[0-9]+]], [[BB:.LBB.*]]
; CHECK: [[BB]]:
; CHECK: mov x[[REG]], xzr
; Do not remove the mov in this case because we do not know if the upper bits
; of the X register are zero.
define i64 @f_WX(i32 %n, i64* nocapture readonly %P) {
entry:
%tobool = icmp eq i32 %n, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
%0 = load i64, i64* %P
br label %if.end
if.end: ; preds = %entry, %if.then
%a.0 = phi i64 [ %0, %if.then ], [ 0, %entry ]
ret i64 %a.0
}
AArch64: improve redundant copy elimination. Mostly, this fixes the bug that if the CBZ guaranteed Xn but Wn was used, we didn't sort out the use-def chain properly. I've also made it check more than just the last instruction for a compatible CBZ (so it can cope without fallthroughs). I'd have liked to do that separately, but it's helps writing the test. Finally, I removed some custom loops in favour of MachineInstr helpers and refactored the control flow to flatten it and avoid possibly quadratic iterations in blocks with many copies. NFC for these, just a general tidy-up. llvm-svn: 261154
2016-02-18 05:16:53 +08:00
; CHECK-LABEL: test_superreg:
; CHECK: cbz x[[REG:[0-9]+]], [[BB:.LBB.*]]
; CHECK: [[BB]]:
; CHECK: str x[[REG]], [x1]
; CHECK-NOT: mov w[[REG]], wzr
; Because we returned w0 but x0 was marked live-in to the block, we didn't
; remove the <kill> on the str leading to a verification failure.
define i32 @test_superreg(i64 %in, i64* %dest) {
%tst = icmp eq i64 %in, 0
br i1 %tst, label %true, label %false
false:
ret i32 42
true:
store volatile i64 %in, i64* %dest
ret i32 0
AArch64: always clear kill flags up to last eliminated copy After r261154, we were only clearing flags if the known-zero register was originally live-in to the basic block, but we have to do it even if not when more than one COPY has been eliminated, otherwise the user of the first COPY may still have <kill> marked. E.g. BB#N: %X0 = COPY %XZR STRXui %X0<kill>, <fi#0> %X0 = COPY %XZR STRXui %X0<kill>, <fi#1> We can eliminate both copies, X0 is not live-in, but we must clear the kill on the first store. Unfortunately, I've been unable to come up with a non-fragile test for this. I've only seen it in the wild with regalloc-created spills, and attempts to reproduce that in a reasonable way run afoul of COPY coalescing. Even volatile asm clobbers were moved around. Should fix the aarch64 bot though. llvm-svn: 261175
2016-02-18 07:07:04 +08:00
}