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[ARM] Add v8m.base pattern for add negative imm 

The v8m.base ISA contains movw, which can operate on an unsigned
16-bit value. Add the pattern that converts an add with a negative
value, that could fit into 16-bits when negated, into a sub with that
positive value.

Differential Revision: https://reviews.llvm.org/D57942

llvm-svn: 353692
This commit is contained in:
Sam Parker 2019-02-11 11:35:42 +00:00
parent ded96df01e
commit 8ff143033a
2 changed files with 46 additions and 13 deletions
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5
llvm/lib/Target/ARM/ARMInstrThumb2.td
View File

@ -2147,6 +2147,11 @@ def : T2Pat<(add GPR:$src, imm0_4095_neg:$imm),
def : T2Pat<(add GPR:$src, imm0_65535_neg:$imm),
(t2SUBrr GPR:$src, (t2MOVi16 (imm_neg_XFORM imm:$imm)))>;
// Do the same for v8m targets since they support movw with a 16-bit value.
def : T1Pat<(add tGPR:$src, imm0_65535_neg:$imm),
(tSUBrr tGPR:$src, (t2MOVi16 (imm_neg_XFORM imm:$imm)))>,
Requires<[HasV8MBaseline]>;
let AddedComplexity = 1 in
def : T2Pat<(ARMaddc rGPR:$src, imm1_255_neg:$imm),
(t2SUBSri rGPR:$src, imm1_255_neg:$imm)>;

54
llvm/test/CodeGen/ARM/sub.ll
View File

@ -1,10 +1,13 @@
; RUN: llc -mtriple=arm-eabi -mcpu=cortex-a8 %s -o - | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-LE
; RUN: llc -mtriple=arm-eabi -mcpu=cortex-a8 %s -show-mc-encoding -o - | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-LE
; RUN: llc -mtriple=armeb-eabi -mcpu=cortex-a8 %s -o - | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-BE
; RUN: llc -mtriple=thumbv6m %s -o - | FileCheck %s --check-prefix=CHECK-V6M
; RUN: llc -mtriple=thumbv8m.base -show-mc-encoding %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-V8M
; RUN: llc -mtriple=thumbv8m.main -show-mc-encoding %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-V8M
; 171 = 0x000000ab
define i64 @f1(i64 %a) {
; CHECK: f1
; CHECK-LE: subs r0, r0, #171
; CHECK-LABEL: f1
; CHECK-LE: subs{{.*}} r0, #171
; CHECK-LE: sbc r1, r1, #0
; CHECK-BE: subs r1, r1, #171
; CHECK-BE: sbc r0, r0, #0
@ -14,8 +17,8 @@ define i64 @f1(i64 %a) {
; 66846720 = 0x03fc0000
define i64 @f2(i64 %a) {
; CHECK: f2
; CHECK-LE: subs r0, r0, #66846720
; CHECK-LABEL: f2
; CHECK-LE: subs{{.*}} r0, r0, #66846720
; CHECK-LE: sbc r1, r1, #0
; CHECK-BE: subs r1, r1, #66846720
; CHECK-BE: sbc r0, r0, #0
@ -25,8 +28,8 @@ define i64 @f2(i64 %a) {
; 734439407618 = 0x000000ab00000002
define i64 @f3(i64 %a) {
; CHECK: f3
; CHECK-LE: subs r0, r0, #2
; CHECK-LABEL: f3
; CHECK-LE: subs{{.*}} r0, #2
; CHECK-LE: sbc r1, r1, #171
; CHECK-BE: subs r1, r1, #2
; CHECK-BE: sbc r0, r0, #171
@ -36,22 +39,47 @@ define i64 @f3(i64 %a) {
define i32 @f4(i32 %x) {
entry:
; CHECK: f4
; CHECK: rsbs
; CHECK-LABEL: f4
; CHECK-LE: rsbs
; CHECK-BE: rsbs
%sub = sub i32 1, %x
%cmp = icmp ugt i32 %sub, 0
%sel = select i1 %cmp, i32 1, i32 %sub
ret i32 %sel
}
; rdar://11726136
define i32 @f5(i32 %x) {
entry:
; CHECK: f5
; CHECK: movw r1, #65535
; CHECK-LABEL: f5:
; CHECK-LE: movw r1, #65535 @ encoding: [0xff,0x1f,0x0f,0xe3]
; CHECK-V8M: movw r1, #65535 @ encoding: [0x4f,0xf6,0xff,0x71]
; CHECK-NOT: movt
; CHECK-NOT: add
; CHECK: sub r0, r0, r1
; CHECK: sub{{.*}} r0, r0, r1
; CHECK-V6M-LABEL: f5
; CHECK-V6M: ldr [[NEG:r[0-1]+]], [[CONST:.[A-Z0-9_]+]]
; CHECK-V6M: add{{.*}} r0, [[NEG]]
; CHECK-V6M: [[CONST]]
; CHECK-V6M: .long 4294901761
%sub = add i32 %x, -65535
ret i32 %sub
}
define i32 @f6(i32 %x) {
entry:
; CHECK-LABEL: f6:
; CHECK-LE: movw r1, #65535 @ encoding: [0xff,0x1f,0x0f,0xe3]
; CHECK-V8M: movw r1, #65535 @ encoding: [0x4f,0xf6,0xff,0x71]
; CHECK-NOT: movt
; CHECK-NOT: sub
; CHECK: add{{.*}} r0, r1
; CHECK-V6M-LABEL: f6
; CHECK-V6M: ldr [[NEG:r[0-1]+]], [[CONST:.[A-Z0-9_]+]]
; CHECK-V6M: add{{.*}} r0, [[NEG]]
; CHECK-V6M: [[CONST]]
; CHECK-V6M: .long 65535
%sub = sub i32 %x, -65535
ret i32 %sub
}