[llvm] r347257 - [InstCombine] Set debug loc on `mergeStoreIntoSuccessor` phi

[Vedant Kumar via llvm-commits]

Author: vedantk
Date: Mon Nov 19 11:55:02 2018
New Revision: 347257

URL: http://llvm.org/viewvc/llvm-project?rev=347257&view=rev
Log:
[InstCombine] Set debug loc on `mergeStoreIntoSuccessor` phi

Assigning a merged debug location to the `mergeStoreIntoSuccessor` phi
improves backtrace quality.

Fixes llvm.org/PR38083.

Added:
    llvm/trunk/test/Transforms/InstCombine/storemerge-dbg.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp?rev=347257&r1=347256&r2=347257&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp Mon Nov 19 11:55:02 2018
@@ -19,6 +19,7 @@
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/MDBuilder.h"
@@ -1600,11 +1601,15 @@ bool InstCombiner::mergeStoreIntoSuccess
 
   // Insert a PHI node now if we need it.
   Value *MergedVal = OtherStore->getOperand(0);
+  // The debug locations of the original instructions might differ. Merge them.
+  DebugLoc MergedLoc = DILocation::getMergedLocation(SI.getDebugLoc(),
+                                                     OtherStore->getDebugLoc());
   if (MergedVal != SI.getOperand(0)) {
     PHINode *PN = PHINode::Create(MergedVal->getType(), 2, "storemerge");
     PN->addIncoming(SI.getOperand(0), SI.getParent());
     PN->addIncoming(OtherStore->getOperand(0), OtherBB);
     MergedVal = InsertNewInstBefore(PN, DestBB->front());
+    PN->setDebugLoc(MergedLoc);
   }
 
   // Advance to a place where it is safe to insert the new store and insert it.
@@ -1613,8 +1618,7 @@ bool InstCombiner::mergeStoreIntoSuccess
                                    SI.isVolatile(), SI.getAlignment(),
                                    SI.getOrdering(), SI.getSyncScopeID());
   InsertNewInstBefore(NewSI, *BBI);
-  // The debug locations of the original instructions might differ. Merge them.
-  NewSI->applyMergedLocation(SI.getDebugLoc(), OtherStore->getDebugLoc());
+  NewSI->setDebugLoc(MergedLoc);
 
   // If the two stores had AA tags, merge them.
   AAMDNodes AATags;

Added: llvm/trunk/test/Transforms/InstCombine/storemerge-dbg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/storemerge-dbg.ll?rev=347257&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/storemerge-dbg.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/storemerge-dbg.ll Mon Nov 19 11:55:02 2018
@@ -0,0 +1,26 @@
+; RUN: opt < %s -debugify -instcombine -S | FileCheck %s
+
+declare i32 @escape(i32)
+
+; CHECK-LABEL: define {{.*}}@foo(
+define i32 @foo() {
+entry:
+  %baz = alloca i32
+  br i1 undef, label %lhs, label %rhs
+
+lhs:
+  store i32 1, i32* %baz
+  br label %cleanup
+
+rhs:
+  store i32 2, i32* %baz
+  br label %cleanup
+
+cleanup:
+  ; CHECK: %storemerge = phi i32 [ 1, %lhs ], [ 2, %rhs ], !dbg [[merge_loc:![0-9]+]]
+  %baz.val = load i32, i32* %baz
+  %ret.val = call i32 @escape(i32 %baz.val)
+  ret i32 %ret.val
+}
+
+; CHECK: [[merge_loc]] = !DILocation(line: 0