[PATCH] [InstCombine] call SimplifyICmpInst with correct context

[Jingyue Wu]

Hi hfinkel, majnemer,

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.

http://reviews.llvm.org/D10695

Files:
  lib/Transforms/InstCombine/InstCombineCompares.cpp
  test/Transforms/InstCombine/pr23809.ll

Index: lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2646,7 +2646,8 @@
     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
Index: test/Transforms/InstCombine/pr23809.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/pr23809.ll
@@ -0,0 +1,13 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; InstCombine should preserve the call to @llvm.assume.
+define i32 @foo(i32 %a, i32 %b) {
+; CHECK-LABEL: @foo(
+  %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
+}
+
+declare void @llvm.assume(i1)

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D10695.28360.patch
Type: text/x-patch
Size: 1104 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150624/fcb26273/attachment.bin>