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GVN: propagate equalities for floating point compares

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Allow optimizations based on FP comparison values in the same way
as integers. 

This resolves PR17713:
http://llvm.org/bugs/show_bug.cgi?id=17713

Differential Revision: http://reviews.llvm.org/D6911



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225660 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2015-01-12 19:29:48 +00:00
parent 728315adf4
commit 2211d38267
3 changed files with 89 additions and 1 deletions
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7
lib/Transforms/Scalar/GVN.cpp
View File

@ -2171,7 +2171,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
// If we are propagating an equality like "(A == B)" == "true" then also
// propagate the equality A == B. When propagating a comparison such as
// "(A >= B)" == "true", replace all instances of "A < B" with "false".
if (ICmpInst *Cmp = dyn_cast<ICmpInst>(LHS)) {
if (CmpInst *Cmp = dyn_cast<CmpInst>(LHS)) {
Value *Op0 = Cmp->getOperand(0), *Op1 = Cmp->getOperand(1);
// If "A == B" is known true, or "A != B" is known false, then replace
@ -2180,6 +2180,11 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS,
(isKnownFalse && Cmp->getPredicate() == CmpInst::ICMP_NE))
Worklist.push_back(std::make_pair(Op0, Op1));
// Handle the floating point versions of equality comparisons too.
if ((isKnownTrue && Cmp->getPredicate() == CmpInst::FCMP_OEQ) ||
(isKnownFalse && Cmp->getPredicate() == CmpInst::FCMP_UNE))
Worklist.push_back(std::make_pair(Op0, Op1));
// If "A >= B" is known true, replace "A < B" with false everywhere.
CmpInst::Predicate NotPred = Cmp->getInversePredicate();
Constant *NotVal = ConstantInt::get(Cmp->getType(), isKnownFalse);

48
test/Transforms/GVN/condprop.ll
View File

@ -144,6 +144,22 @@ different:
ret i1 %cmp3
}
; CHECK-LABEL: @test6_fp(
define i1 @test6_fp(float %x, float %y) {
%cmp2 = fcmp une float %x, %y
%cmp = fcmp oeq float %x, %y
%cmp3 = fcmp oeq float %x, %y
br i1 %cmp, label %same, label %different
same:
; CHECK: ret i1 false
ret i1 %cmp2
different:
; CHECK: ret i1 false
ret i1 %cmp3
}
; CHECK-LABEL: @test7(
define i1 @test7(i32 %x, i32 %y) {
%cmp = icmp sgt i32 %x, %y
@ -160,6 +176,22 @@ different:
ret i1 %cmp3
}
; CHECK-LABEL: @test7_fp(
define i1 @test7_fp(float %x, float %y) {
%cmp = fcmp ogt float %x, %y
br i1 %cmp, label %same, label %different
same:
%cmp2 = fcmp ule float %x, %y
; CHECK: ret i1 false
ret i1 %cmp2
different:
%cmp3 = fcmp ogt float %x, %y
; CHECK: ret i1 false
ret i1 %cmp3
}
; CHECK-LABEL: @test8(
define i1 @test8(i32 %x, i32 %y) {
%cmp2 = icmp sle i32 %x, %y
@ -176,6 +208,22 @@ different:
ret i1 %cmp3
}
; CHECK-LABEL: @test8_fp(
define i1 @test8_fp(float %x, float %y) {
%cmp2 = fcmp ule float %x, %y
%cmp = fcmp ogt float %x, %y
%cmp3 = fcmp ogt float %x, %y
br i1 %cmp, label %same, label %different
same:
; CHECK: ret i1 false
ret i1 %cmp2
different:
; CHECK: ret i1 false
ret i1 %cmp3
}
; PR1768
; CHECK-LABEL: @test9(
define i32 @test9(i32 %i, i32 %j) {

35
test/Transforms/GVN/edge.ll
View File

@ -58,3 +58,38 @@ bb2:
; CHECK: call void @g(i1 %y)
ret void
}
define double @fcmp_oeq(double %x, double %y) {
entry:
%cmp = fcmp oeq double %y, 2.0
br i1 %cmp, label %if, label %return
if:
%div = fdiv double %x, %y
br label %return
return:
%retval.0 = phi double [ %div, %if ], [ %x, %entry ]
ret double %retval.0
; CHECK-LABEL: define double @fcmp_oeq(
; CHECK: %div = fdiv double %x, 2.000000e+00
}
define double @fcmp_une(double %x, double %y) {
entry:
%cmp = fcmp une double %y, 2.0
br i1 %cmp, label %return, label %else
else:
%div = fdiv double %x, %y
br label %return
return:
%retval.0 = phi double [ %div, %else ], [ %x, %entry ]
ret double %retval.0
; CHECK-LABEL: define double @fcmp_une(
; CHECK: %div = fdiv double %x, 2.000000e+00
}