forked from OSchip/llvm-project
[ARM] Mark -1 as cheap in xor's for thumb1
We can always convert xor %a, -1 into MVN, even in thumb 1 where the -1 would not otherwise be considered a cheap constant. This prevents the -1's from being pulled out into constants and potentially hoisted. Differential Revision: https://reviews.llvm.org/D43451 llvm-svn: 325573
This commit is contained in:
David Green
parent
76e5023dd3
commit
056476497e
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@ -126,6 +126,13 @@ int ARMTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
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return 0;
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}
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// xor a, -1 can always be folded to MVN
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if (Opcode == Instruction::Xor) {
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int64_t NegImm = Imm.getSExtValue();
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if (NegImm == -1)
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return 0;
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}
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return getIntImmCost(Imm, Ty);
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}
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@ -0,0 +1,193 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -mtriple=thumbv6m-eabi -asm-verbose=false %s -o - | FileCheck %s
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define void @test8(i8* %a) {
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; CHECK-LABEL: test8:
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; CHECK: ldrb r1, [r0]
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; CHECK-NEXT: mvns r1, r1
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; CHECK-NEXT: strb r1, [r0]
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; CHECK-NEXT: bx lr
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%x = load i8, i8* %a
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%xn = xor i8 %x, -1
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store i8 %xn, i8* %a
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ret void
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}
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define void @test8_2(i8* %a, i8* %b) {
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; CHECK-LABEL: test8_2:
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; CHECK: ldrb r2, [r1]
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; CHECK-NEXT: ldrb r3, [r0]
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; CHECK-NEXT: mvns r3, r3
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; CHECK-NEXT: strb r3, [r0]
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; CHECK-NEXT: mvns r0, r2
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; CHECK-NEXT: strb r0, [r1]
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; CHECK-NEXT: bx lr
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%x = load i8, i8* %a
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%y = load i8, i8* %b
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%xn = xor i8 %x, -1
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%yn = xor i8 %y, -1
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store i8 %xn, i8* %a
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store i8 %yn, i8* %b
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ret void
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}
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define void @loop8(i8* %a) {
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; CHECK-LABEL: loop8:
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; CHECK: movs r1, #0
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; CHECK-NEXT: .LBB2_1:
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; CHECK-NEXT: ldrb r2, [r0, r1]
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; CHECK-NEXT: mvns r2, r2
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; CHECK-NEXT: strb r2, [r0, r1]
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; CHECK-NEXT: adds r1, r1, #1
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; CHECK-NEXT: cmp r1, #10
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; CHECK-NEXT: bne .LBB2_1
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; CHECK-NEXT: bx lr
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entry:
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br label %for.body
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for.body:
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%i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds i8, i8* %a, i32 %i
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%x = load i8, i8* %arrayidx
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%xn = xor i8 %x, -1
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store i8 %xn, i8* %arrayidx
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%inc = add nuw nsw i32 %i, 1
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%exitcond = icmp eq i32 %inc, 10
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup:
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ret void
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}
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define void @loop8_2(i8* %a, i8* %b) {
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; CHECK-LABEL: loop8_2:
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; CHECK: .save {r4, lr}
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; CHECK-NEXT: push {r4, lr}
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; CHECK-NEXT: movs r2, #0
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; CHECK-NEXT: .LBB3_1:
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; CHECK-NEXT: ldrb r3, [r1, r2]
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; CHECK-NEXT: ldrb r4, [r0, r2]
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; CHECK-NEXT: mvns r4, r4
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; CHECK-NEXT: strb r4, [r0, r2]
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; CHECK-NEXT: mvns r3, r3
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; CHECK-NEXT: strb r3, [r1, r2]
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; CHECK-NEXT: adds r2, r2, #1
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; CHECK-NEXT: cmp r2, #10
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; CHECK-NEXT: bne .LBB3_1
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; CHECK-NEXT: pop {r4, pc}
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entry:
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br label %for.body
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for.body:
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%i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds i8, i8* %a, i32 %i
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%arrayidx2 = getelementptr inbounds i8, i8* %b, i32 %i
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%x = load i8, i8* %arrayidx
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%y = load i8, i8* %arrayidx2
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%xn = xor i8 %x, -1
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%yn = xor i8 %y, -1
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store i8 %xn, i8* %arrayidx
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store i8 %yn, i8* %arrayidx2
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%inc = add nuw nsw i32 %i, 1
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%exitcond = icmp eq i32 %inc, 10
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup:
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ret void
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}
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define void @test32(i32* %a) {
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; CHECK-LABEL: test32:
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; CHECK: ldr r1, [r0]
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; CHECK-NEXT: mvns r1, r1
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; CHECK-NEXT: str r1, [r0]
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; CHECK-NEXT: bx lr
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%x = load i32, i32* %a
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%xn = xor i32 %x, -1
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store i32 %xn, i32* %a
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ret void
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}
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define void @test32_2(i32* %a, i32* %b) {
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; CHECK-LABEL: test32_2:
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; CHECK: ldr r2, [r1]
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; CHECK-NEXT: ldr r3, [r0]
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; CHECK-NEXT: mvns r3, r3
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; CHECK-NEXT: str r3, [r0]
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; CHECK-NEXT: mvns r0, r2
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; CHECK-NEXT: str r0, [r1]
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; CHECK-NEXT: bx lr
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%x = load i32, i32* %a
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%y = load i32, i32* %b
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%xn = xor i32 %x, -1
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%yn = xor i32 %y, -1
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store i32 %xn, i32* %a
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store i32 %yn, i32* %b
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ret void
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}
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define void @loop32(i32* %a) {
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; CHECK-LABEL: loop32:
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; CHECK: movs r1, #0
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; CHECK-NEXT: .LBB6_1:
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; CHECK-NEXT: ldr r2, [r0, r1]
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; CHECK-NEXT: mvns r2, r2
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; CHECK-NEXT: str r2, [r0, r1]
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; CHECK-NEXT: adds r1, r1, #4
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; CHECK-NEXT: cmp r1, #40
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; CHECK-NEXT: bne .LBB6_1
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; CHECK-NEXT: bx lr
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entry:
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br label %for.body
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for.body:
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%i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds i32, i32* %a, i32 %i
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%x = load i32, i32* %arrayidx
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%xn = xor i32 %x, -1
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store i32 %xn, i32* %arrayidx
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%inc = add nuw nsw i32 %i, 1
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%exitcond = icmp eq i32 %inc, 10
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup:
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ret void
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}
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define void @loop32_2(i32* %a, i32* %b) {
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; CHECK-LABEL: loop32_2:
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; CHECK: .save {r4, lr}
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; CHECK-NEXT: push {r4, lr}
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; CHECK-NEXT: movs r2, #0
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; CHECK-NEXT: .LBB7_1:
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; CHECK-NEXT: ldr r3, [r1, r2]
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; CHECK-NEXT: ldr r4, [r0, r2]
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; CHECK-NEXT: mvns r4, r4
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; CHECK-NEXT: str r4, [r0, r2]
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; CHECK-NEXT: mvns r3, r3
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; CHECK-NEXT: str r3, [r1, r2]
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; CHECK-NEXT: adds r2, r2, #4
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; CHECK-NEXT: cmp r2, #40
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; CHECK-NEXT: bne .LBB7_1
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; CHECK-NEXT: pop {r4, pc}
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entry:
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br label %for.body
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for.body:
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%i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds i32, i32* %a, i32 %i
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%arrayidx2 = getelementptr inbounds i32, i32* %b, i32 %i
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%x = load i32, i32* %arrayidx
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%y = load i32, i32* %arrayidx2
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%xn = xor i32 %x, -1
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%yn = xor i32 %y, -1
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store i32 %xn, i32* %arrayidx
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store i32 %yn, i32* %arrayidx2
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%inc = add nuw nsw i32 %i, 1
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%exitcond = icmp eq i32 %inc, 10
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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for.cond.cleanup:
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ret void
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}
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