[llvm] r335121 - [InstCombine] ignore debuginfo when removing redundant assumes (PR37726)

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Wed Jun 20 06:22:26 2018
New Revision: 335121

URL: http://llvm.org/viewvc/llvm-project?rev=335121&view=rev
Log:
[InstCombine] ignore debuginfo when removing redundant assumes (PR37726)

This is similar to:
rL335083

Fixes::
https://bugs.llvm.org/show_bug.cgi?id=37726


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/assume.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=335121&r1=335120&r2=335121&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Wed Jun 20 06:22:26 2018
@@ -3672,9 +3672,11 @@ Instruction *InstCombiner::visitCallInst
     break;
   case Intrinsic::assume: {
     Value *IIOperand = II->getArgOperand(0);
-    // Remove an assume if it is immediately followed by an identical assume.
-    if (match(II->getNextNode(),
-              m_Intrinsic<Intrinsic::assume>(m_Specific(IIOperand))))
+    // Remove an assume if it is followed by an identical assume.
+    // TODO: Do we need this? Unless there are conflicting assumptions, the
+    // computeKnownBits(IIOperand) below here eliminates redundant assumes.
+    Instruction *Next = II->getNextNonDebugInstruction();
+    if (match(Next, m_Intrinsic<Intrinsic::assume>(m_Specific(IIOperand))))
       return eraseInstFromFunction(CI);
 
     // Canonicalize assume(a && b) -> assume(a); assume(b);

Modified: llvm/trunk/test/Transforms/InstCombine/assume.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/assume.ll?rev=335121&r1=335120&r2=335121&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/assume.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/assume.ll Wed Jun 20 06:22:26 2018
@@ -295,16 +295,15 @@ define i32 @assumption_conflicts_with_kn
 ; FIXME:
 ; PR37726 - https://bugs.llvm.org/show_bug.cgi?id=37726
 ; There's a loophole in eliminating a redundant assumption when
-; we have conflicting assumptions. Verify that debuginfo doesn't 
+; we have conflicting assumptions. Verify that debuginfo doesn't
 ; get in the way of the fold.
- 
+
 define void @debug_interference(i8 %x) {
 ; CHECK-LABEL: @debug_interference(
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i8 [[X:%.*]], 0
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 [[CMP1]])
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
-; CHECK-NEXT:    tail call void @llvm.assume(i1 false)
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 5, metadata !7, metadata !DIExpression()), !dbg !9
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 false)
 ; CHECK-NEXT:    ret void