[libc-commits] [libc] ce368e1 - [libc][NFC] Workaround clang assertion in inline asm

[Alex Brachet via libc-commits]

Author: Alex Brachet
Date: 2022-01-25T16:39:55Z
New Revision: ce368e1aa51f3d9f0a5f6ff0be3c02a9cf1e2d2e

URL: https://github.com/llvm/llvm-project/commit/ce368e1aa51f3d9f0a5f6ff0be3c02a9cf1e2d2e
DIFF: https://github.com/llvm/llvm-project/commit/ce368e1aa51f3d9f0a5f6ff0be3c02a9cf1e2d2e.diff

LOG: [libc][NFC] Workaround clang assertion in inline asm

The clobber list "cc" is added to inline assembly to workaround a clang assertion that triggers when building with a clang built with assertions enabled. See bug [53391](https://github.com/llvm/llvm-project/issues/53391).

See https://godbolt.org/z/z3bc6a9PM showing functionally same output assembly.

Reviewed By: sivachandra, lntue

Differential Revision: https://reviews.llvm.org/D118099

Added: 
    

Modified: 
    libc/src/math/x86_64/cos.cpp
    libc/src/math/x86_64/sin.cpp
    libc/src/math/x86_64/tan.cpp

Removed: 
    


################################################################################
diff  --git a/libc/src/math/x86_64/cos.cpp b/libc/src/math/x86_64/cos.cpp
index 9e7e7227c6b1d..3b785a2f78cdf 100644
--- a/libc/src/math/x86_64/cos.cpp
+++ b/libc/src/math/x86_64/cos.cpp
@@ -13,7 +13,7 @@ namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(double, cos, (double x)) {
   double result;
-  __asm__ __volatile__("fcos" : "=t"(result) : "f"(x));
+  __asm__ __volatile__("fcos" : "=t"(result) : "f"(x) : "cc");
   return result;
 }
 

diff  --git a/libc/src/math/x86_64/sin.cpp b/libc/src/math/x86_64/sin.cpp
index 22774f278956e..e94aa1a3f0925 100644
--- a/libc/src/math/x86_64/sin.cpp
+++ b/libc/src/math/x86_64/sin.cpp
@@ -13,7 +13,7 @@ namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(double, sin, (double x)) {
   double result;
-  __asm__ __volatile__("fsin" : "=t"(result) : "f"(x));
+  __asm__ __volatile__("fsin" : "=t"(result) : "f"(x) : "cc");
   return result;
 }
 

diff  --git a/libc/src/math/x86_64/tan.cpp b/libc/src/math/x86_64/tan.cpp
index 9146473741f95..0503af7a16dde 100644
--- a/libc/src/math/x86_64/tan.cpp
+++ b/libc/src/math/x86_64/tan.cpp
@@ -16,7 +16,7 @@ LLVM_LIBC_FUNCTION(double, tan, (double x)) {
   double one;
   // The fptan instruction pushes the number 1 on to the FP stack after
   // computing tan. So, we read out the one before popping the actual result.
-  __asm__ __volatile__("fptan" : "=t"(one) : "f"(x));
+  __asm__ __volatile__("fptan" : "=t"(one) : "f"(x) : "cc");
   __asm__ __volatile__("fstpl %0" : "=m"(result));
   return result;
 }