From 529f49db93c039b0ea7ec7c8ad9b5067cd8e7e78 Mon Sep 17 00:00:00 2001
From: Jingyue Wu <jingyue@google.com>
Date: Thu, 25 Jun 2015 20:14:47 +0000
Subject: [PATCH] [InstCombine] call SimplifyICmpInst with correct context

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
---
 .../InstCombine/InstCombineCompares.cpp       |  6 +++--
 test/Transforms/InstCombine/pr23809.ll        | 22 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 test/Transforms/InstCombine/pr23809.ll

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index f53eeef1dae..010b7b57c3e 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -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'
diff --git a/test/Transforms/InstCombine/pr23809.ll b/test/Transforms/InstCombine/pr23809.ll
new file mode 100644
index 00000000000..06c7ce20ba8
--- /dev/null
+++ b/test/Transforms/InstCombine/pr23809.ll
@@ -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)
-- 
2.34.1