[BOLT][Instrumentation] Preserve red zone for functions with tail calls only

Allow a function with tail calls only to clobber its red zone.

Fixes https://github.com/llvm/llvm-project/issues/61114.

Reviewed By: #bolt, yota9

Differential Revision: https://reviews.llvm.org/D145202

1 files changed, 7 insertions, 6 deletions

diff --git a/bolt/lib/Passes/Instrumentation.cpp b/bolt/lib/Passes/Instrumentation.cpp
index a0350b14d2b5..c6e1bf9e6b16 100644
--- a/bolt/lib/Passes/Instrumentation.cpp
+++ b/bolt/lib/Passes/Instrumentation.cpp
@@ -357,12 +357,13 @@ void Instrumentation::instrumentFunction(BinaryFunction &Function,
   // instructions to protect the red zone
   bool IsLeafFunction = true;
   DenseSet<const BinaryBasicBlock *> InvokeBlocks;
-  for (auto BBI = Function.begin(), BBE = Function.end(); BBI != BBE; ++BBI) {
-    for (auto I = BBI->begin(), E = BBI->end(); I != E; ++I) {
-      if (BC.MIB->isCall(*I)) {
-        if (BC.MIB->isInvoke(*I))
-          InvokeBlocks.insert(&*BBI);
-        IsLeafFunction = false;
+  for (const BinaryBasicBlock &BB : Function) {
+    for (const MCInst &Inst : BB) {
+      if (BC.MIB->isCall(Inst)) {
+        if (BC.MIB->isInvoke(Inst))
+          InvokeBlocks.insert(&BB);
+        if (!BC.MIB->isTailCall(Inst))
+          IsLeafFunction = false;
       }
     }
   }