From: Reid Kleckner <rnk@google.com>
Date: Tue, 14 Feb 2017 21:38:17 +0000 (+0000)
Subject: MS inline asm: Filter MXCSR out of the inferred clobber list
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d418b54ac44ba3ed94302aaf3ac1e26de8b078c2;p=clang

MS inline asm: Filter MXCSR out of the inferred clobber list

Since r295004, LLVM has started modelling this new register, but we
don't have GCC constraint inline asm spellings for it yet.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295107 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Parse/ParseStmtAsm.cpp b/lib/Parse/ParseStmtAsm.cpp
index 59e96d982a..85cd22fef4 100644
--- a/lib/Parse/ParseStmtAsm.cpp
+++ b/lib/Parse/ParseStmtAsm.cpp
@@ -621,10 +621,11 @@ StmtResult Parser::ParseMicrosoftAsmStatement(SourceLocation AsmLoc) {
                                MII.get(), IP.get(), Callback))
     return StmtError();
 
-  // Filter out "fpsw".  Clang doesn't accept it, and it always lists flags and
-  // fpsr as clobbers.
-  auto End = std::remove(Clobbers.begin(), Clobbers.end(), "fpsw");
-  Clobbers.erase(End, Clobbers.end());
+  // Filter out "fpsw" and "mxcsr". They aren't valid GCC asm clobber
+  // constraints. Clang always adds fpsr to the clobber list anyway.
+  llvm::erase_if(Clobbers, [](const std::string &C) {
+    return C == "fpsw" || C == "mxcsr";
+  });
 
   // Build the vector of clobber StringRefs.
   ClobberRefs.insert(ClobberRefs.end(), Clobbers.begin(), Clobbers.end());
diff --git a/test/CodeGen/ms-inline-asm.c b/test/CodeGen/ms-inline-asm.c
index 6db0cff50d..69b732c9ac 100644
--- a/test/CodeGen/ms-inline-asm.c
+++ b/test/CodeGen/ms-inline-asm.c
@@ -649,6 +649,14 @@ void label6(){
   // CHECK: call void asm sideeffect inteldialect "jmp {{.*}}__MSASMLABEL_.${:uid}__label\0A\09{{.*}}__MSASMLABEL_.${:uid}__label:", "~{dirflag},~{fpsr},~{flags}"()
 }
 
+// Don't include mxcsr in the clobber list.
+void mxcsr() {
+  char buf[4096];
+  __asm fxrstor buf
+}
+// CHECK-LABEL: define void @mxcsr
+// CHECK: call void asm sideeffect inteldialect "fxrstor byte ptr $0", "=*m,~{dirflag},~{fpsr},~{flags}"
+
 typedef union _LARGE_INTEGER {
   struct {
     unsigned int LowPart;