[llvm] r179316 - Optimize icmp involving addition better
Renato Golin
renato.golin at linaro.org
Wed Apr 17 02:39:23 PDT 2013
Folks,
This patch is not agreeing with some Cortex-A9/15 specific optimization, as
it fails only when I specify either on --mcpu the command line option.
Before I start digging the huge code, can anyone of you spot any direct
problem of this patch against A9/15 specific optimizations?
I'm trying to reduce the test into a manageable and reproducible source
file, but this can take a while. If I don't hear from anyone until Friday,
I'm afraid I'll have to revert the patch until we can figure out what's
going on. We need a clean trunk to produce the LLVM ARM binaries for 3.3
release.
cheers,
--renato
On 16 April 2013 14:01, Renato Golin <renato.golin at linaro.org> wrote:
> 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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>
>
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