[msan][x86] Fix shadow for FP80 or long double (#72706)

FP80 is passed using stack.

Author: vitalybuka

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

@@ -4748,6 +4748,8 @@ struct VarArgAMD64Helper : public VarArgHelperBase {
   ArgKind classifyArgument(Value *arg) {
     // A very rough approximation of X86_64 argument classification rules.
     Type *T = arg->getType();
+    if (T->isX86_FP80Ty())
+      return AK_Memory;
     if (T->isFPOrFPVectorTy() || T->isX86_MMXTy())
       return AK_FloatingPoint;
     if (T->isIntegerTy() && T->getPrimitiveSizeInBits() <= 64)

llvm/test/Instrumentation/MemorySanitizer/X86/vararg_shadow.ll

@@ -205,8 +205,8 @@ define linkonce_odr dso_local void @_Z4testIeEvT_(x86_fp80 noundef %arg) sanitiz
 ; CHECK-NEXT:    store i80 [[_MSLD]], ptr @__msan_param_tls, align 8
 ; CHECK-NEXT:    store i32 0, ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_param_tls to i64), i64 16) to ptr), align 8
 ; CHECK-NEXT:    store i80 [[_MSLD]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_param_tls to i64), i64 24) to ptr), align 8
-; CHECK-NEXT:    store i80 [[_MSLD]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 64) to ptr), align 8
-; CHECK-NEXT:    store i64 0, ptr @__msan_va_arg_overflow_size_tls, align 8
+; CHECK-NEXT:    store i80 [[_MSLD]], ptr inttoptr (i64 add (i64 ptrtoint (ptr @__msan_va_arg_tls to i64), i64 176) to ptr), align 8
+; CHECK-NEXT:    store i64 16, ptr @__msan_va_arg_overflow_size_tls, align 8
 ; CHECK-NEXT:    call void (x86_fp80, i32, ...) @_Z5test2IeEvT_iz(x86_fp80 noundef [[TMP7]], i32 noundef 1, x86_fp80 noundef [[TMP7]])
 ; CHECK-NEXT:    ret void
 ;