[PATCH] D85573: [CGAtomic] Mark atomic libcall functions `nounwind`

[Gui Andrade via Phabricator via cfe-commits]

guiand created this revision.
guiand added reviewers: rsmith, eugenis.
Herald added subscribers: cfe-commits, jfb.
Herald added a project: clang.
guiand requested review of this revision.

  These functions won't ever unwind. This is useful for MemorySanitizer
  as it simplifies handling __atomic_load in particular.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85573

Files:
  clang/lib/CodeGen/CGAtomic.cpp
  clang/test/CodeGen/atomic_ops.c


Index: clang/test/CodeGen/atomic_ops.c
===================================================================
--- clang/test/CodeGen/atomic_ops.c
+++ clang/test/CodeGen/atomic_ops.c
@@ -26,6 +26,9 @@
 
 }
 
+// LIBCALL: declare void @__atomic_load(i32, i8*, i8*, i32) [[LC_ATTRS:#[0-9]+]]
+// LIBCALL: declare i1 @__atomic_compare_exchange(i32, i8*, i8*, i8*, i32, i32) [[LC_ATTRS:#[0-9]+]]
+
 extern _Atomic _Bool b;
 
 _Bool bar() {
@@ -53,6 +56,8 @@
   x += y;
 }
 
+// LIBCALL: declare void @__atomic_store(i32, i8*, i8*, i32) [[LC_ATTRS:#[0-9]+]]
+
 _Atomic(int) compound_add(_Atomic(int) in) {
 // CHECK-LABEL: @compound_add
 // CHECK: [[OLD:%.*]] = atomicrmw add i32* {{.*}}, i32 5 seq_cst
@@ -107,3 +112,5 @@
 
   return (in *= 5);
 }
+
+// LIBCALL: [[LC_ATTRS]] = { nounwind }
Index: clang/lib/CodeGen/CGAtomic.cpp
===================================================================
--- clang/lib/CodeGen/CGAtomic.cpp
+++ clang/lib/CodeGen/CGAtomic.cpp
@@ -307,7 +307,12 @@
   const CGFunctionInfo &fnInfo =
     CGF.CGM.getTypes().arrangeBuiltinFunctionCall(resultType, args);
   llvm::FunctionType *fnTy = CGF.CGM.getTypes().GetFunctionType(fnInfo);
-  llvm::FunctionCallee fn = CGF.CGM.CreateRuntimeFunction(fnTy, fnName);
+  llvm::AttributeList fnAttrs;
+  fnAttrs = fnAttrs.addAttribute(CGF.getLLVMContext(),
+                                 llvm::AttributeList::FunctionIndex,
+                                 llvm::Attribute::NoUnwind);
+  llvm::FunctionCallee fn =
+      CGF.CGM.CreateRuntimeFunction(fnTy, fnName, fnAttrs);
   auto callee = CGCallee::forDirect(fn);
   return CGF.EmitCall(fnInfo, callee, ReturnValueSlot(), args);
 }


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