[llvm] [RemoveDIs][DebugInfo] Correctly visit DPValues in StackInfoBuilder::visit (PR #81247)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer updated https://github.com/llvm/llvm-project/pull/81247

>From 6970a1b4fe5b6c3eb186f6f6c86b3df336db52d6 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <Stephen.Tozer at Sony.com>
Date: Fri, 9 Feb 2024 09:53:58 +0000
Subject: [PATCH 1/2] Correctly visit DPValues in StackInfoBuilder::visit

---
 .../Transforms/Utils/MemoryTaggingSupport.cpp | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp b/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
index 648a5276a3d60a..43366950d8df1e 100644
--- a/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
+++ b/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp
@@ -110,6 +110,20 @@ Instruction *getUntagLocationIfFunctionExit(Instruction &Inst) {
 }
 
 void StackInfoBuilder::visit(Instruction &Inst) {
+  // Check for non-intrinsic debug-info records.
+  for (auto &DPV : Inst.getDbgValueRange()) {
+    for (Value *V : DPV.location_ops()) {
+      if (auto *AI = dyn_cast_or_null<AllocaInst>(V)) {
+        if (!isInterestingAlloca(*AI))
+          continue;
+        AllocaInfo &AInfo = Info.AllocasToInstrument[AI];
+        auto &DPVVec = AInfo.DbgVariableRecords;
+        if (DPVVec.empty() || DPVVec.back() != &DPV)
+          DPVVec.push_back(&DPV);
+      }
+    }
+  }
+
   if (CallInst *CI = dyn_cast<CallInst>(&Inst)) {
     if (CI->canReturnTwice()) {
       Info.CallsReturnTwice = true;
@@ -150,20 +164,6 @@ void StackInfoBuilder::visit(Instruction &Inst) {
     }
   }
 
-  // Check for non-intrinsic debug-info records.
-  for (auto &DPV : Inst.getDbgValueRange()) {
-    for (Value *V : DPV.location_ops()) {
-      if (auto *AI = dyn_cast_or_null<AllocaInst>(V)) {
-        if (!isInterestingAlloca(*AI))
-          continue;
-        AllocaInfo &AInfo = Info.AllocasToInstrument[AI];
-        auto &DPVVec = AInfo.DbgVariableRecords;
-        if (DPVVec.empty() || DPVVec.back() != &DPV)
-          DPVVec.push_back(&DPV);
-      }
-    }
-  }
-
   Instruction *ExitUntag = getUntagLocationIfFunctionExit(Inst);
   if (ExitUntag)
     Info.RetVec.push_back(ExitUntag);

>From f0b5d0bd61d5b7be32c871902edc020c06a6ce37 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <Stephen.Tozer at Sony.com>
Date: Mon, 12 Feb 2024 13:11:35 +0000
Subject: [PATCH 2/2] Modify test to fail if DPValues left unprocessed

---
 .../HWAddressSanitizer/dbg-declare-tag-offset.ll           | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/llvm/test/Instrumentation/HWAddressSanitizer/dbg-declare-tag-offset.ll b/llvm/test/Instrumentation/HWAddressSanitizer/dbg-declare-tag-offset.ll
index d5e362bc800ad8..50bad19250267c 100644
--- a/llvm/test/Instrumentation/HWAddressSanitizer/dbg-declare-tag-offset.ll
+++ b/llvm/test/Instrumentation/HWAddressSanitizer/dbg-declare-tag-offset.ll
@@ -1,5 +1,10 @@
 ; RUN: opt -passes=hwasan -S -o - %s | FileCheck %s
 
+;; Also test with RemoveDIs to verify that debug intrinsics immediately
+;; preceding an alloca (or other instruction of interest to stack tagging) will
+;; be correctly processed.
+; RUN: opt --try-experimental-debuginfo-iterators -passes=hwasan -S -o - %s | FileCheck %s
+
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64--linux-android"
 
@@ -12,11 +17,11 @@ entry:
   %nodebug2 = alloca ptr
   %nodebug3 = alloca ptr
   %a = alloca ptr
-  %b = alloca ptr
   ; CHECK: @llvm.dbg.declare{{.*}} !DIExpression(DW_OP_LLVM_tag_offset, 32)
   call void @llvm.dbg.declare(metadata ptr %a, metadata !12, metadata !DIExpression()), !dbg !14
   ; CHECK: @llvm.dbg.declare{{.*}} !DIExpression(DW_OP_LLVM_tag_offset, 32)
   call void @llvm.dbg.declare(metadata ptr %a, metadata !12, metadata !DIExpression()), !dbg !14
+  %b = alloca ptr
   ; CHECK: @llvm.dbg.declare{{.*}} !DIExpression(DW_OP_LLVM_tag_offset, 96)
   call void @llvm.dbg.declare(metadata ptr %b, metadata !13, metadata !DIExpression()), !dbg !14
   ; CHECK: @llvm.dbg.declare{{.*}} !DIExpression(DW_OP_LLVM_tag_offset, 96)