Changeset 175514 in webkit for trunk/Source/JavaScriptCore/offlineasm/arm64.rb

Timestamp:

Nov 3, 2014, 11:36:15 PM (11 years ago)

Author:

[email protected]

Message:

Workaround for Cortex-A53 erratum 835769
​https://bugs.webkit.org/show_bug.cgi?id=138315

Patch by Akos Kiss <​[email protected]> 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.

File:

• trunk/Source/JavaScriptCore/offlineasm/arm64.rb (modified) (3 diffs)

trunk/Source/JavaScriptCore/offlineasm/arm64.rb

@@ -229 +229 @@
 end
 
+# Workaround for Cortex-A53 erratum (835769)
+def arm64CortexA53Fix835769(list)
+    newList = []
+    lastOpcodeUnsafe = false
+
+    list.each {
+        | node |
+        if node.is_a? Instruction
+            case node.opcode
+            when /^store/, /^load/
+                # List all macro instructions that can be lowered to a load, store or prefetch ARM64 assembly instruction
+                lastOpcodeUnsafe = true
+            when  "muli", "mulp", "mulq", "smulli"
+                # List all macro instructions that can be lowered to a 64-bit multiply-accumulate ARM64 assembly instruction
+                # (defined as one of MADD, MSUB, SMADDL, SMSUBL, UMADDL or UMSUBL).
+                if lastOpcodeUnsafe
+                    newList << Instruction.new(node.codeOrigin, "nopCortexA53Fix835769", [])
+                end
+                lastOpcodeUnsafe = false
+            else
+                lastOpcodeUnsafe = false
+            end
+        end
+        newList << node
+    }
+    newList
+end
+
 class Sequence
     def getModifiedListARM64
@@ -285 +313 @@
         result = assignRegistersToTemporaries(result, :gpr, ARM64_EXTRA_GPRS)
         result = assignRegistersToTemporaries(result, :fpr, ARM64_EXTRA_FPRS)
+        result = arm64CortexA53Fix835769(result)
         return result
     end
@@ -838 +867 @@
             $asm.puts "dmb sy"
         when "pcrtoaddr"
-          $asm.puts "adr #{operands[1].arm64Operand(:ptr)}, #{operands[0].value}"
+            $asm.puts "adr #{operands[1].arm64Operand(:ptr)}, #{operands[0].value}"
+        when "nopCortexA53Fix835769"
+            $asm.putStr("#if CPU(ARM64_CORTEXA53)")
+            $asm.puts "nop"
+            $asm.putStr("#endif")
         else
             lowerDefault