commit edb9fbb78a18d796e497e83ff912b19d064cf5a1
author Richard Smith <richard-llvm@metafoo.co.uk> Fri Sep 07 21:24:27 2018 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Fri Sep 07 21:24:27 2018 +0000
tree 9cd20a4bb5a38c68523bee758bfa7603e0a90e15
parent f98c2c5e6d65fb2a0194fd3ea9f52d793035f63c

Make -Watomic-alignment say whether the atomic operation was oversized
or misaligned.

llvm-svn: 341710

clang/include/clang/Basic/DiagnosticSemaKinds.td

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 78d1b0f..9945b22 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -7093,8 +7093,8 @@
 def err_atomic_op_has_invalid_synch_scope : Error<
   "synchronization scope argument to atomic operation is invalid">;
 def warn_atomic_op_misaligned : Warning<
-  "misaligned or large atomic operation may incur significant performance penalty">,
-  InGroup<DiagGroup<"atomic-alignment">>;
+  "%select{large|misaligned}0 atomic operation may incur "
+  "significant performance penalty">, InGroup<DiagGroup<"atomic-alignment">>;
 
 def err_overflow_builtin_must_be_int : Error<
   "operand argument to overflow builtin must be an integer (%0 invalid)">;

clang/lib/CodeGen/CGAtomic.cpp

diff --git a/clang/lib/CodeGen/CGAtomic.cpp b/clang/lib/CodeGen/CGAtomic.cpp
index eaf29df..5b63b3f 100644
--- a/clang/lib/CodeGen/CGAtomic.cpp
+++ b/clang/lib/CodeGen/CGAtomic.cpp
@@ -765,11 +765,15 @@
   std::tie(sizeChars, alignChars) = getContext().getTypeInfoInChars(AtomicTy);
   uint64_t Size = sizeChars.getQuantity();
   unsigned MaxInlineWidthInBits = getTarget().getMaxAtomicInlineWidth();
-  bool UseLibcall = ((Ptr.getAlignment() % sizeChars) != 0 ||
-                     getContext().toBits(sizeChars) > MaxInlineWidthInBits);
 
-  if (UseLibcall)
-    CGM.getDiags().Report(E->getBeginLoc(), diag::warn_atomic_op_misaligned);
+  bool Oversized = getContext().toBits(sizeChars) > MaxInlineWidthInBits;
+  bool Misaligned = (Ptr.getAlignment() % sizeChars) != 0;
+  bool UseLibcall = Misaligned | Oversized;
+
+  if (UseLibcall) {
+    CGM.getDiags().Report(E->getBeginLoc(), diag::warn_atomic_op_misaligned)
+        << !Oversized;
+  }
 
   llvm::Value *Order = EmitScalarExpr(E->getOrder());
   llvm::Value *Scope =

clang/test/CodeGen/atomics-sema-alignment.c

diff --git a/clang/test/CodeGen/atomics-sema-alignment.c b/clang/test/CodeGen/atomics-sema-alignment.c
index 364743d..9443af3 100644
--- a/clang/test/CodeGen/atomics-sema-alignment.c
+++ b/clang/test/CodeGen/atomics-sema-alignment.c
@@ -12,10 +12,10 @@
 
 void func(IntPair *p) {
   IntPair res;
-  __atomic_load(p, &res, 0); // expected-warning {{misaligned or large atomic operation may incur significant performance penalty}}
-  __atomic_store(p, &res, 0); // expected-warning {{misaligned or large atomic operation may incur significant performance penalty}}
-  __atomic_fetch_add((unaligned_int *)p, 1, 2); // expected-warning {{misaligned or large atomic operation may incur significant performance penalty}}
-  __atomic_fetch_sub((unaligned_int *)p, 1, 3); // expected-warning {{misaligned or large atomic operation may incur significant performance penalty}}
+  __atomic_load(p, &res, 0); // expected-warning {{misaligned atomic operation may incur significant performance penalty}}
+  __atomic_store(p, &res, 0); // expected-warning {{misaligned atomic operation may incur significant performance penalty}}
+  __atomic_fetch_add((unaligned_int *)p, 1, 2); // expected-warning {{misaligned atomic operation may incur significant performance penalty}}
+  __atomic_fetch_sub((unaligned_int *)p, 1, 3); // expected-warning {{misaligned atomic operation may incur significant performance penalty}}
 }
 
 void func1(LongStruct *p) {