[llvm] [SROA] Support dbg_declare_value (PR #225902)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-debuginfo

Author: Ellis Hoag (ellishg)

<details>
<summary>Changes</summary>

Handle `#dbg_declare_value` in the SROA pass to avoid an `undef` argument, similar to https://github.com/llvm/llvm-project/pull/94070. This prevents an assert in the `instcombine` pass down the line. 

---
Full diff: https://github.com/llvm/llvm-project/pull/225902.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Scalar/SROA.cpp (+8) 
- (modified) llvm/test/DebugInfo/Generic/sroa-alloca-offset.ll (+21) 


``````````diff
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index f12ab1e590678..e5a5b9109edd2 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -5946,6 +5946,14 @@ insertNewDbgInst(DIBuilder &DIB, DbgVariableRecord *Orig, AllocaInst *NewAddr,
     return;
   }
 
+  if (Orig->isDbgDeclareValue()) {
+    DbgVariableRecord *DVR = DbgVariableRecord::createDVRDeclareValue(
+        NewAddr, Orig->getVariable(), NewFragmentExpr, Orig->getDebugLoc());
+    BeforeInst->getParent()->insertDbgRecordBefore(DVR,
+                                                   BeforeInst->getIterator());
+    return;
+  }
+
   // Apply a DIAssignID to the store if it doesn't already have it.
   if (!NewAddr->hasMetadata(LLVMContext::MD_DIAssignID)) {
     NewAddr->setMetadata(LLVMContext::MD_DIAssignID,
diff --git a/llvm/test/DebugInfo/Generic/sroa-alloca-offset.ll b/llvm/test/DebugInfo/Generic/sroa-alloca-offset.ll
index 6718711f83e04..79e5cc4b3cf3c 100644
--- a/llvm/test/DebugInfo/Generic/sroa-alloca-offset.ll
+++ b/llvm/test/DebugInfo/Generic/sroa-alloca-offset.ll
@@ -204,6 +204,21 @@ entry:
   ret i32 %2
 }
 
+; COMMON-LABEL: @fun5
+define i32 @fun5(ptr %source) !dbg !70 {
+entry:
+  %t = alloca %struct.four, align 4
+    #dbg_declare_value(ptr %t, !74, !DIExpression(DW_OP_plus_uconst, 8), !75)
+  ; COMMON: [[FUN5_LOCAL:%.*]] = alloca %struct.two, align 8
+  ; COMMON: #dbg_declare_value(ptr [[FUN5_LOCAL]], ![[t:[0-9]+]], !DIExpression(DW_OP_LLVM_fragment, 0, 64),
+  ; COMMON-NOT: #dbg_assign
+  call void @llvm.memcpy.p0.p0.i64(ptr align 4 %t, ptr align 4 %source, i64 16, i1 false)
+  %1 = getelementptr inbounds %struct.four, ptr %t, i32 0, i32 0
+  %2 = getelementptr inbounds %struct.two, ptr %1, i32 0, i32 1
+  %3 = load i32, ptr %2, align 4
+  ret i32 %3
+}
+
 ; COMMON-DAG: ![[x0]] = !DILocalVariable(name: "x",
 ; COMMON-DAG: ![[y0]] = !DILocalVariable(name: "y",
 ; COMMON-DAG: ![[A0]] = !DILocalVariable(scope:
@@ -221,6 +236,8 @@ entry:
 ; COMMON-DAG: ![[q]] = !DILocalVariable(name: "q"
 ; COMMON-DAG: ![[r]] = !DILocalVariable(name: "r"
 
+; COMMON-DAG: ![[t]] = !DILocalVariable(name: "t"
+
 declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg)
 
 !llvm.dbg.cu = !{!2}
@@ -273,3 +290,7 @@ declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias
 !67 = !DILocalVariable(name: "p", scope: !65, file: !3, line: 9, type: !13)
 !68 = !DILocalVariable(name: "q", scope: !65, file: !3, line: 9, type: !13)
 !69 = !DILocalVariable(name: "r", scope: !65, file: !3, line: 9, type: !13)
+!70 = distinct !DISubprogram(name: "fun5", scope: !3, file: !3, line: 1, type: !24, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2)
+!73 = !DICompositeType(tag: DW_TAG_structure_type, name: "declare_value", size: 256)
+!74 = !DILocalVariable(name: "t", scope: !70, file: !3, line: 1, type: !73)
+!75 = !DILocation(line: 1, column: 1, scope: !70)

``````````

</details>


https://github.com/llvm/llvm-project/pull/225902