[TSan] Fix atomicrmw xchg with pointer and floats (#85228)

atomicrmw xchg also accepts pointer and floating-point values. To handle
those, insert necessary casts to and from integer. This is what we do
for cmpxchg as well.

Fixes #85226.

Author: nikic

llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp

@@ -752,11 +752,12 @@ bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
     const unsigned ByteSize = 1U << Idx;
     const unsigned BitSize = ByteSize * 8;
     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
-    Value *Args[] = {Addr,
-                     IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
+    Value *Val = RMWI->getValOperand();
+    Value *Args[] = {Addr, IRB.CreateBitOrPointerCast(Val, Ty),
                      createOrdering(&IRB, RMWI->getOrdering())};
-    CallInst *C = CallInst::Create(F, Args);
-    ReplaceInstWithInst(I, C);
+    Value *C = IRB.CreateCall(F, Args);
+    I->replaceAllUsesWith(IRB.CreateBitOrPointerCast(C, Val->getType()));
+    I->eraseFromParent();
   } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
     Value *Addr = CASI->getPointerOperand();
     Type *OrigOldValTy = CASI->getNewValOperand()->getType();

llvm/test/Instrumentation/ThreadSanitizer/atomic.ll

@@ -78,6 +78,26 @@ entry:
 ; CHECK-LABEL: atomic8_xchg_monotonic
 ; CHECK: call i8 @__tsan_atomic8_exchange(ptr %a, i8 0, i32 0), !dbg
 
+define void @atomic8_xchg_monotonic_ptr(ptr %a, ptr %b) nounwind uwtable {
+entry:
+  atomicrmw xchg ptr %a, ptr %b monotonic, !dbg !7
+  ret void, !dbg !7
+}
+; CHECK-LABEL: atomic8_xchg_monotonic_ptr
+; CHECK: [[ARG:%.*]] = ptrtoint ptr %b to i64, !dbg
+; CHECK: [[RES:%.*]] = call i64 @__tsan_atomic64_exchange(ptr %a, i64 [[ARG]], i32 0), !dbg
+; CHECK: [[CAST:%.*]] = inttoptr i64 [[RES]] to ptr, !dbg
+
+define void @atomic8_xchg_monotonic_float(ptr %a, float %b) nounwind uwtable {
+entry:
+  atomicrmw xchg ptr %a, float %b monotonic, !dbg !7
+  ret void, !dbg !7
+}
+; CHECK-LABEL: atomic8_xchg_monotonic_float
+; CHECK: [[ARG:%.*]] = bitcast float %b to i32, !dbg
+; CHECK: [[RES:%.*]] = call i32 @__tsan_atomic32_exchange(ptr %a, i32 [[ARG]], i32 0), !dbg
+; CHECK: [[CAST:%.*]] = bitcast i32 [[RES]] to float, !dbg
+
 define void @atomic8_add_monotonic(ptr %a) nounwind uwtable {
 entry:
   atomicrmw add ptr %a, i8 0 monotonic, !dbg !7