Workaround for Cortex-A53 erratum 835769
https://bugs.webkit.org/show_bug.cgi?id=138315
Patch by Akos Kiss <akiss@inf.u-szeged.hu> on 2014-11-03
Reviewed by Filip Pizlo.
This patch introduces CMake variable and preprocessor macro
WTF_CPU_ARM64_CORTEXA53 with the aim of enabling Cortex-A53-specific
.:
code paths, if set true.
* Source/cmake/OptionsCommon.cmake:
Add -mfix-cortex-a53-835769 to the compiler flags if compiler supports
it.
* Source/cmakeconfig.h.cmake:
#cmakedefine01 for WTF_CPU_ARM64_CORTEXA53
Source/JavaScriptCore:
code paths, if set true. The patch also implements one case where such
code paths are needed: the workaround for Cortex-A53 erratum 835769. If
WTF_CPU_ARM64_CORTEXA53 is set then:
- CMake checks whether the compiler already has support for a workaround
and adds -mfix-cortex-a53-835769 to the compiler flags if so,
- the ARM64 backend of offlineasm inserts a nop between memory and
multiply-accumulate instructions, and
- the ARM64 assembler also inserts a nop between memory and (64-bit)
multiply-accumulate instructions.
* assembler/ARM64Assembler.h:
(JSC::ARM64Assembler::madd):
Call nopCortexA53Fix835769() to insert a nop if CPU(ARM64_CORTEXA53) and
if necessary.
(JSC::ARM64Assembler::msub): Likewise.
(JSC::ARM64Assembler::smaddl): Likewise.
(JSC::ARM64Assembler::smsubl): Likewise.
(JSC::ARM64Assembler::umaddl): Likewise.
(JSC::ARM64Assembler::umsubl): Likewise.
(JSC::ARM64Assembler::nopCortexA53Fix835769):
Added. Insert a nop if the previously emitted instruction was a load, a
store, or a prefetch, and if the current instruction is 64-bit.
* offlineasm/arm64.rb:
Add the arm64CortexA53Fix835769 phase and call it from
getModifiedListARM64 to insert nopCortexA53Fix835769 between appropriate
macro instructions. Also, lower nopCortexA53Fix835769 to nop if
CPU(ARM64_CORTEXA53), to nothing otherwise.
* offlineasm/instructions.rb:
Define macro instruction nopFixCortexA53Err835769.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@175514 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/offlineasm/instructions.rb b/Source/JavaScriptCore/offlineasm/instructions.rb
index 8728ee4..1d0d867 100644
--- a/Source/JavaScriptCore/offlineasm/instructions.rb
+++ b/Source/JavaScriptCore/offlineasm/instructions.rb
@@ -266,7 +266,8 @@
ARM64_INSTRUCTIONS =
[
- "pcrtoaddr" # Address from PC relative offset - adr instruction
+ "pcrtoaddr", # Address from PC relative offset - adr instruction
+ "nopFixCortexA53Err835769" # nop on Cortex-A53 (nothing otherwise)
]
RISC_INSTRUCTIONS =
