[SROA] Preserve DebugLoc when rewriting alloca partitions

When rewriting an alloca partition copy the DL from the
old alloca over the the new one.

Differential Revision: https://reviews.llvm.org/D48640

llvm-svn: 335904

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -4029,6 +4029,8 @@ AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
     NewAI = new AllocaInst(
       SliceTy, AI.getType()->getAddressSpace(), nullptr, Alignment,
         AI.getName() + ".sroa." + Twine(P.begin() - AS.begin()), &AI);
+    // Copy the old AI debug location over to the new one.
+    NewAI->setDebugLoc(AI.getDebugLoc());
     ++NumNewAllocas;
   }
 

llvm/test/Transforms/SROA/alignment.ll

@@ -1,4 +1,6 @@
 ; RUN: opt < %s -sroa -S | FileCheck %s
+; RUN: opt -debugify -sroa -S < %s | FileCheck %s -check-prefix DEBUGLOC
+
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64"
 
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i1)
@@ -35,6 +37,13 @@ define void @test2() {
 ; CHECK: store i8 42, i8* %{{.*}}
 ; CHECK: ret void
 
+; Check that when sroa rewrites the alloca partition
+; it preserves the original DebugLocation.
+; DEBUGLOC-LABEL: @test2(
+; DEBUGLOC: {{.*}} = alloca {{.*}} !dbg ![[DbgLoc:[0-9]+]]
+;
+; DEBUGLOC: ![[DbgLoc]] = !DILocation(
+
 entry:
   %a = alloca { i8, i8, i8, i8 }, align 2
   %gep1 = getelementptr { i8, i8, i8, i8 }, { i8, i8, i8, i8 }* %a, i32 0, i32 1