[clang] 8fa2e93 - [clang] Do not merge traps in functions annotated optnone

[Henrik G. Olsson via cfe-commits]

Author: Henrik G. Olsson
Date: 2022-11-30T15:06:32+01:00
New Revision: 8fa2e93538595e1ff973110cb3f301b65bc9d2eb

URL: https://github.com/llvm/llvm-project/commit/8fa2e93538595e1ff973110cb3f301b65bc9d2eb
DIFF: https://github.com/llvm/llvm-project/commit/8fa2e93538595e1ff973110cb3f301b65bc9d2eb.diff

LOG: [clang] Do not merge traps in functions annotated optnone

This aligns the behaviour with that of disabling optimisations for the
translation unit entirely. Not merging the traps allows us to keep
separate debug information for each, improving the debugging experience
when finding the cause for a ubsan trap.

Differential Revision: https://reviews.llvm.org/D137714

Added: 
    

Modified: 
    clang/lib/CodeGen/CGExpr.cpp
    clang/test/CodeGen/ubsan-trap-debugloc.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index d2d2ace66cee3..5021fc77e7b9b 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -3550,7 +3550,8 @@ void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked,
     TrapBBs.resize(CheckHandlerID + 1);
   llvm::BasicBlock *&TrapBB = TrapBBs[CheckHandlerID];
 
-  if (!CGM.getCodeGenOpts().OptimizationLevel || !TrapBB) {
+  if (!CGM.getCodeGenOpts().OptimizationLevel || !TrapBB ||
+      (CurCodeDecl && CurCodeDecl->hasAttr<OptimizeNoneAttr>())) {
     TrapBB = createBasicBlock("trap");
     Builder.CreateCondBr(Checked, Cont, TrapBB);
     EmitBlock(TrapBB);

diff  --git a/clang/test/CodeGen/ubsan-trap-debugloc.c b/clang/test/CodeGen/ubsan-trap-debugloc.c
index d73cf73fc7c39..4cad708b0ca50 100644
--- a/clang/test/CodeGen/ubsan-trap-debugloc.c
+++ b/clang/test/CodeGen/ubsan-trap-debugloc.c
@@ -2,9 +2,23 @@
 
 
 void foo(volatile int a) {
+  // CHECK-LABEL: @foo
   // CHECK: call void @llvm.ubsantrap(i8 0){{.*}} !dbg [[LOC:![0-9]+]]
   a = a + 1;
   a = a + 1;
 }
 
+void bar(volatile int a) __attribute__((optnone)) {
+  // CHECK-LABEL: @bar
+  // CHECK: call void @llvm.ubsantrap(i8 0){{.*}} !dbg [[LOC2:![0-9]+]]
+  // CHECK: call void @llvm.ubsantrap(i8 0){{.*}} !dbg [[LOC3:![0-9]+]]
+  a = a + 1;
+  a = a + 1;
+}
+
+// With optimisations enabled the traps are merged and need to share a debug location
 // CHECK: [[LOC]] = !DILocation(line: 0
+
+// With optimisations disabled the traps are not merged and retain accurate debug locations
+// CHECK: [[LOC2]] = !DILocation(line: 15, column: 9
+// CHECK: [[LOC3]] = !DILocation(line: 16, column: 9