[llvm] r179316 - Optimize icmp involving addition better
Renato Golin
renato.golin at linaro.org
Tue Apr 16 06:01:31 PDT 2013
Hi David,
This patch broke one of out buildbots:
http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/532
I have reverted you patch locally and the test pass again, but it's not
easy to spot what's wrong with it.
Do you have access to ARM hardware?
cheers,
--renato
On 11 April 2013 21:05, David Majnemer <david.majnemer at gmail.com> wrote:
> Author: majnemer
> Date: Thu Apr 11 15:05:46 2013
> New Revision: 179316
>
> URL: http://llvm.org/viewvc/llvm-project?rev=179316&view=rev
> Log:
> Optimize icmp involving addition better
>
> Allows LLVM to optimize sequences like the following:
>
> %add = add nsw i32 %x, 1
> %cmp = icmp sgt i32 %add, %y
>
> into:
>
> %cmp = icmp sge i32 %x, %y
>
> as well as:
>
> %add1 = add nsw i32 %x, 20
> %add2 = add nsw i32 %y, 57
> %cmp = icmp sge i32 %add1, %add2
>
> into:
>
> %add = add nsw i32 %y, 37
> %cmp = icmp sle i32 %cmp, %x
>
> Modified:
> llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
> llvm/trunk/test/Transforms/InstCombine/icmp.ll
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=179316&r1=179315&r2=179316&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Thu Apr
> 11 15:05:46 2013
> @@ -2487,6 +2487,55 @@ Instruction *InstCombiner::visitICmpInst
> return new ICmpInst(Pred, Y, Z);
> }
>
> + // icmp slt (X + -1), Y -> icmp sle X, Y
> + if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
> + match(B, m_AllOnes()))
> + return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
> +
> + // icmp sge (X + -1), Y -> icmp sgt X, Y
> + if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
> + match(B, m_AllOnes()))
> + return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
> +
> + // icmp sle (X + 1), Y -> icmp slt X, Y
> + if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE &&
> + match(B, m_One()))
> + return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
> +
> + // icmp sgt (X + 1), Y -> icmp sge X, Y
> + if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT &&
> + match(B, m_One()))
> + return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
> +
> + // if C1 has greater magnitude than C2:
> + // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
> + // s.t. C3 = C1 - C2
> + //
> + // if C2 has greater magnitude than C1:
> + // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
> + // s.t. C3 = C2 - C1
> + if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
> + (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
> + if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
> + if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
> + const APInt &AP1 = C1->getValue();
> + const APInt &AP2 = C2->getValue();
> + if (AP1.isNegative() == AP2.isNegative()) {
> + APInt AP1Abs = C1->getValue().abs();
> + APInt AP2Abs = C2->getValue().abs();
> + if (AP1Abs.uge(AP2Abs)) {
> + ConstantInt *C3 = Builder->getInt(AP1 - AP2);
> + Value *NewAdd = Builder->CreateNSWAdd(A, C3);
> + return new ICmpInst(Pred, NewAdd, C);
> + } else {
> + ConstantInt *C3 = Builder->getInt(AP2 - AP1);
> + Value *NewAdd = Builder->CreateNSWAdd(C, C3);
> + return new ICmpInst(Pred, A, NewAdd);
> + }
> + }
> + }
> +
> +
> // Analyze the case when either Op0 or Op1 is a sub instruction.
> // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are
> null).
> A = 0; B = 0; C = 0; D = 0;
>
> Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=179316&r1=179315&r2=179316&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Thu Apr 11 15:05:46 2013
> @@ -886,3 +886,55 @@ define i1 @icmp_mul0_ne0(i32 %x) {
> %cmp = icmp ne i32 %mul, 0
> ret i1 %cmp
> }
> +
> +; CHECK: @icmp_sub1_sge
> +; CHECK-NEXT: icmp sgt i32 %x, %y
> +define i1 @icmp_sub1_sge(i32 %x, i32 %y) {
> + %sub = add nsw i32 %x, -1
> + %cmp = icmp sge i32 %sub, %y
> + ret i1 %cmp
> +}
> +
> +; CHECK: @icmp_add1_sgt
> +; CHECK-NEXT: icmp sge i32 %x, %y
> +define i1 @icmp_add1_sgt(i32 %x, i32 %y) {
> + %add = add nsw i32 %x, 1
> + %cmp = icmp sgt i32 %add, %y
> + ret i1 %cmp
> +}
> +
> +; CHECK: @icmp_sub1_slt
> +; CHECK-NEXT: icmp sle i32 %x, %y
> +define i1 @icmp_sub1_slt(i32 %x, i32 %y) {
> + %sub = add nsw i32 %x, -1
> + %cmp = icmp slt i32 %sub, %y
> + ret i1 %cmp
> +}
> +
> +; CHECK: @icmp_add1_sle
> +; CHECK-NEXT: icmp slt i32 %x, %y
> +define i1 @icmp_add1_sle(i32 %x, i32 %y) {
> + %add = add nsw i32 %x, 1
> + %cmp = icmp sle i32 %add, %y
> + ret i1 %cmp
> +}
> +
> +; CHECK: @icmp_add20_sge_add57
> +; CHECK-NEXT: [[ADD:%[a-z0-9]+]] = add nsw i32 %y, 37
> +; CHECK-NEXT: icmp sle i32 [[ADD]], %x
> +define i1 @icmp_add20_sge_add57(i32 %x, i32 %y) {
> + %1 = add nsw i32 %x, 20
> + %2 = add nsw i32 %y, 57
> + %cmp = icmp sge i32 %1, %2
> + ret i1 %cmp
> +}
> +
> +; CHECK: @icmp_sub57_sge_sub20
> +; CHECK-NEXT: [[SUB:%[a-z0-9]+]] = add nsw i32 %x, -37
> +; CHECK-NEXT: icmp sge i32 [[SUB]], %y
> +define i1 @icmp_sub57_sge_sub20(i32 %x, i32 %y) {
> + %1 = add nsw i32 %x, -57
> + %2 = add nsw i32 %y, -20
> + %cmp = icmp sge i32 %1, %2
> + ret i1 %cmp
> +}
>
>
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