lkail created this revision.
lkail added reviewers: jsji, nemanjai, w2yehia, shchenz, PowerPC.
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XL's `__compare_and_swap` has a weird behavior that
> In either case, the contents of the memory location specified by addr are
> copied into the memory location specified by old_val_addr.
This patch let clang's implementation follow this behavior.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D106344
Files:
clang/lib/CodeGen/CGBuiltin.cpp
clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
Index: clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
===================================================================
--- clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
+++ clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
@@ -19,6 +19,7 @@
// CHECK-NEXT: [[TMP2:%.*]] = cmpxchg weak volatile i32* [[A_ADDR]], i32
[[TMP1]], i32 [[TMP0]] monotonic monotonic, align 4
// CHECK-NEXT: [[TMP3:%.*]] = extractvalue { i32, i1 } [[TMP2]], 0
// CHECK-NEXT: [[TMP4:%.*]] = extractvalue { i32, i1 } [[TMP2]], 1
+// CHECK-NEXT: store i32 [[TMP3]], i32* [[B_ADDR]], align 4
// CHECK-NEXT: ret void
//
void test_builtin_ppc_compare_and_swap(int a, int b, int c) {
@@ -39,6 +40,7 @@
// CHECK-NEXT: [[TMP2:%.*]] = cmpxchg weak volatile i64* [[A_ADDR]], i64
[[TMP1]], i64 [[TMP0]] monotonic monotonic, align 8
// CHECK-NEXT: [[TMP3:%.*]] = extractvalue { i64, i1 } [[TMP2]], 0
// CHECK-NEXT: [[TMP4:%.*]] = extractvalue { i64, i1 } [[TMP2]], 1
+// CHECK-NEXT: store i64 [[TMP3]], i64* [[B_ADDR]], align 8
// CHECK-NEXT: ret void
//
void test_builtin_ppc_compare_and_swaplp(long a, long b, long c) {
Index: clang/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- clang/lib/CodeGen/CGBuiltin.cpp
+++ clang/lib/CodeGen/CGBuiltin.cpp
@@ -15590,6 +15590,15 @@
auto Pair = EmitAtomicCompareExchange(
LV, RValue::get(OldVal), RValue::get(Ops[2]), E->getExprLoc(),
llvm::AtomicOrdering::Monotonic, llvm::AtomicOrdering::Monotonic,
true);
+ // FIXME:
+ // Unlike c11's atomic_compare_exchange, accroding to
+ //
https://www.ibm.com/docs/en/xl-c-and-cpp-aix/16.1?topic=functions-compare-swap-compare-swaplp
+ // > In either case, the contents of the memory location specified by addr
+ // > are copied into the memory location specified by old_val_addr.
+ // But it hasn't specified storing to OldValAddr is atomic or not and
+ // which order to use.
+ Value *LoadedVal = Pair.first.getScalarVal();
+ Builder.CreateStore(LoadedVal, OldValAddr);
return Pair.second;
}
case PPC::BI__builtin_ppc_fetch_and_add:
Index: clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
===================================================================
--- clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
+++ clang/test/CodeGen/builtins-ppc-xlcompat-cas.c
@@ -19,6 +19,7 @@
// CHECK-NEXT: [[TMP2:%.*]] = cmpxchg weak volatile i32* [[A_ADDR]], i32 [[TMP1]], i32 [[TMP0]] monotonic monotonic, align 4
// CHECK-NEXT: [[TMP3:%.*]] = extractvalue { i32, i1 } [[TMP2]], 0
// CHECK-NEXT: [[TMP4:%.*]] = extractvalue { i32, i1 } [[TMP2]], 1
+// CHECK-NEXT: store i32 [[TMP3]], i32* [[B_ADDR]], align 4
// CHECK-NEXT: ret void
//
void test_builtin_ppc_compare_and_swap(int a, int b, int c) {
@@ -39,6 +40,7 @@
// CHECK-NEXT: [[TMP2:%.*]] = cmpxchg weak volatile i64* [[A_ADDR]], i64 [[TMP1]], i64 [[TMP0]] monotonic monotonic, align 8
// CHECK-NEXT: [[TMP3:%.*]] = extractvalue { i64, i1 } [[TMP2]], 0
// CHECK-NEXT: [[TMP4:%.*]] = extractvalue { i64, i1 } [[TMP2]], 1
+// CHECK-NEXT: store i64 [[TMP3]], i64* [[B_ADDR]], align 8
// CHECK-NEXT: ret void
//
void test_builtin_ppc_compare_and_swaplp(long a, long b, long c) {
Index: clang/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- clang/lib/CodeGen/CGBuiltin.cpp
+++ clang/lib/CodeGen/CGBuiltin.cpp
@@ -15590,6 +15590,15 @@
auto Pair = EmitAtomicCompareExchange(
LV, RValue::get(OldVal), RValue::get(Ops[2]), E->getExprLoc(),
llvm::AtomicOrdering::Monotonic, llvm::AtomicOrdering::Monotonic, true);
+ // FIXME:
+ // Unlike c11's atomic_compare_exchange, accroding to
+ // https://www.ibm.com/docs/en/xl-c-and-cpp-aix/16.1?topic=functions-compare-swap-compare-swaplp
+ // > In either case, the contents of the memory location specified by addr
+ // > are copied into the memory location specified by old_val_addr.
+ // But it hasn't specified storing to OldValAddr is atomic or not and
+ // which order to use.
+ Value *LoadedVal = Pair.first.getScalarVal();
+ Builder.CreateStore(LoadedVal, OldValAddr);
return Pair.second;
}
case PPC::BI__builtin_ppc_fetch_and_add:
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