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[InstCombine] call SimplifyICmpInst with correct context

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Summary:
Fixes PR23809. Without passing the context to SimplifyICmpInst, we would
use the assume to prove that the condition feeding the assume is
trivially true (see isValidAssumeForContext in ValueTracking.cpp),
causing the removal of the assume which may be useful for later
optimizations.

Test Plan: pr23800.ll

Reviewers: hfinkel, majnemer

Reviewed By: hfinkel

Subscribers: henryhu, llvm-commits, wengxt, broune, meheff, eliben

Differential Revision: http://reviews.llvm.org/D10695

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240683 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jingyue Wu 2015-06-25 20:14:47 +00:00
parent 1de6f369b3
commit 529f49db93
2 changed files with 26 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2646,7 +2646,8 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
Changed = true;
}
if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AC))
if (Value *V =
SimplifyICmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AC, &I))
return ReplaceInstUsesWith(I, V);
// comparing -val or val with non-zero is the same as just comparing val
@ -3927,7 +3928,8 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AC))
if (Value *V =
SimplifyFCmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AC, &I))
return ReplaceInstUsesWith(I, V);
// Simplify 'fcmp pred X, X'

22
test/Transforms/InstCombine/pr23809.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
; InstCombine should preserve the call to @llvm.assume.
define i32 @icmp(i32 %a, i32 %b) {
; CHECK-LABEL: @icmp(
%sum = add i32 %a, %b
%1 = icmp sge i32 %sum, 0
call void @llvm.assume(i1 %1)
; CHECK: call void @llvm.assume
ret i32 %sum
}
define float @fcmp(float %a, float %b) {
; CHECK-LABEL: @fcmp(
%sum = fadd float %a, %b
%1 = fcmp oge float %sum, 0.0
call void @llvm.assume(i1 %1)
; CHECK: call void @llvm.assume
ret float %sum
}
declare void @llvm.assume(i1)