Changeset 231301 in webkit

Timestamp:

May 3, 2018 4:58:50 AM (6 years ago)

Author:

commit-queue@webkit.org

Message:

Disable usage of fused multiply-add instructions for JSC with compiler flag
​https://bugs.webkit.org/show_bug.cgi?id=184909

Patch by Dominik Infuehr <​dinfuehr@igalia.com> on 2018-05-03
Reviewed by Yusuke Suzuki.

Adds -ffp-contract as compiler flag for building JSC. This ensures that functions
like parseInt() do not return slightly different results depending on whether the
compiler was able to use fused multiply-add instructions or not.

• CMakeLists.txt:

Location:

trunk/Source/JavaScriptCore

Files:

• CMakeLists.txt (modified) (1 diff)
• ChangeLog (modified) (1 diff)

trunk/Source/JavaScriptCore/CMakeLists.txt

@@ -1180 +1180 @@
 WEBKIT_INCLUDE_CONFIG_FILES_IF_EXISTS()
 
+if (COMPILER_IS_GCC_OR_CLANG)
+    # Avoid using fused multiply-add instructions since this could give different results
+    # for e.g. parseInt depending on the platform and compilation flags.
+    WEBKIT_ADD_TARGET_CXX_FLAGS(JavaScriptCore -ffp-contract=off)
+endif ()
+
 WEBKIT_MAKE_FORWARDING_HEADERS(JavaScriptCore
     FILES ${JavaScriptCore_PUBLIC_FRAMEWORK_HEADERS}

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2018-05-03  Dominik Infuehr  <dinfuehr@igalia.com>
+
+        Disable usage of fused multiply-add instructions for JSC with compiler flag
+        https://bugs.webkit.org/show_bug.cgi?id=184909
+
+        Reviewed by Yusuke Suzuki.
+
+        Adds -ffp-contract as compiler flag for building JSC. This ensures that functions
+        like parseInt() do not return slightly different results depending on whether the
+        compiler was able to use fused multiply-add instructions or not.
+
+        * CMakeLists.txt:
+
 2018-05-02  Yusuke Suzuki  <utatane.tea@gmail.com>