Title: [272140] trunk/Source/WTF
- Revision
- 272140
- Author
- [email protected]
- Date
- 2021-02-01 04:43:39 -0800 (Mon, 01 Feb 2021)
Log Message
clang Linux build cannot link because of __builtin_mul_overflow
https://bugs.webkit.org/show_bug.cgi?id=190208
Since r183319, __builtin_mul_overflow is used with gcc or clang in WTF/wtf/CheckedArithmetic.h
This leads to a link failure when WebKit is built on Linux with clang and the libgcc runtime,
because of an undefined reference to the __mulodi4 symbol.
This is because clang generates code using the __mulodi4 symbol for __builtin_mul_overflow.
But this symbol is available only in compiler-rt, and not in the libgcc runtime used by most
Linux distributions of clang.
See also this upstream clang bug: https://bugs.llvm.org/show_bug.cgi?id=28629
Patch by Olivier Blin <[email protected]> on 2021-02-01
Reviewed by Mark Lam.
* wtf/CheckedArithmetic.h: Do not use __builtin_mul_overflow with clang on Linux for ARM
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (272139 => 272140)
--- trunk/Source/WTF/ChangeLog 2021-02-01 11:04:22 UTC (rev 272139)
+++ trunk/Source/WTF/ChangeLog 2021-02-01 12:43:39 UTC (rev 272140)
@@ -1,3 +1,23 @@
+2021-02-01 Olivier Blin <[email protected]>
+
+ clang Linux build cannot link because of __builtin_mul_overflow
+ https://bugs.webkit.org/show_bug.cgi?id=190208
+
+ Since r183319, __builtin_mul_overflow is used with gcc or clang in WTF/wtf/CheckedArithmetic.h
+
+ This leads to a link failure when WebKit is built on Linux with clang and the libgcc runtime,
+ because of an undefined reference to the __mulodi4 symbol.
+
+ This is because clang generates code using the __mulodi4 symbol for __builtin_mul_overflow.
+ But this symbol is available only in compiler-rt, and not in the libgcc runtime used by most
+ Linux distributions of clang.
+
+ See also this upstream clang bug: https://bugs.llvm.org/show_bug.cgi?id=28629
+
+ Reviewed by Mark Lam.
+
+ * wtf/CheckedArithmetic.h: Do not use __builtin_mul_overflow with clang on Linux for ARM
+
2021-01-31 Yusuke Suzuki <[email protected]>
Date.parse returns non-integral time value
Modified: trunk/Source/WTF/wtf/CheckedArithmetic.h (272139 => 272140)
--- trunk/Source/WTF/wtf/CheckedArithmetic.h 2021-02-01 11:04:22 UTC (rev 272139)
+++ trunk/Source/WTF/wtf/CheckedArithmetic.h 2021-02-01 12:43:39 UTC (rev 272140)
@@ -31,6 +31,13 @@
#include <stdint.h>
#include <type_traits>
+/* On Linux with clang, libgcc is usually used instead of compiler-rt, and it does
+ * not provide the __mulodi4 symbol used by clang for __builtin_mul_overflow
+ */
+#if COMPILER(GCC) || (COMPILER(CLANG) && !(CPU(ARM) && OS(LINUX)))
+#define USE_MUL_OVERFLOW 1
+#endif
+
/* Checked<T>
*
* This class provides a mechanism to perform overflow-safe integer arithmetic
@@ -360,7 +367,7 @@
static inline bool multiply(LHS lhs, RHS rhs, ResultType& result) WARN_UNUSED_RETURN
{
-#if COMPILER(GCC_COMPATIBLE)
+#if USE(MUL_OVERFLOW)
ResultType temp;
if (__builtin_mul_overflow(lhs, rhs, &temp))
return false;
@@ -442,7 +449,7 @@
static inline bool multiply(LHS lhs, RHS rhs, ResultType& result) WARN_UNUSED_RETURN
{
-#if COMPILER(GCC_COMPATIBLE)
+#if USE(MUL_OVERFLOW)
ResultType temp;
if (__builtin_mul_overflow(lhs, rhs, &temp))
return false;
@@ -514,7 +521,7 @@
static inline bool multiply(int64_t lhs, int64_t rhs, ResultType& result)
{
-#if COMPILER(GCC_COMPATIBLE)
+#if USE(MUL_OVERFLOW)
ResultType temp;
if (__builtin_mul_overflow(lhs, rhs, &temp))
return false;
_______________________________________________
webkit-changes mailing list
[email protected]
https://lists.webkit.org/mailman/listinfo/webkit-changes
