Modified: trunk/Source/_javascript_Core/ChangeLog (240240 => 240241)
--- trunk/Source/_javascript_Core/ChangeLog 2019-01-21 20:15:53 UTC (rev 240240)
+++ trunk/Source/_javascript_Core/ChangeLog 2019-01-21 20:50:59 UTC (rev 240241)
@@ -1,3 +1,22 @@
+2019-01-20 Yusuke Suzuki <[email protected]>
+
+ [JSC] sub op with 0 should be optimized
+ https://bugs.webkit.org/show_bug.cgi?id=190751
+
+ Reviewed by Mark Lam.
+
+ LLInt sometimes emit `subp 0, %rxx`. For example, `maxFrameExtentForSlowPathCall` is 0 in X86_64, ARM64, and ARM64E.
+ So `subp maxFrameExtentForSlowPathCall sp` becomes `subp 0, %rsp`. While `addp 0, %rsp` is removed in offlineasm,
+ sub operation does not have such an optimization. This patch applies the same optimization to sub operation already
+ done in add operation. Since the CPU flags changed in offlineasm's these operations are not considered (if these flags
+ are required, we use special branch operations instead), this optimization is sane.
+
+ One problem is that zero-extension of the 32bit register in 64bit architecture. If the instruction emission is skipped,
+ this won't be happen. Currently, we align our sub to add operation: we skip emission in this case.
+
+ * offlineasm/arm64.rb:
+ * offlineasm/x86.rb:
+
2019-01-20 Saam Barati <[email protected]>
DFG: When inlining DataView set* intrinsics we need to set undefined as our result
Modified: trunk/Source/_javascript_Core/offlineasm/arm64.rb (240240 => 240241)
--- trunk/Source/_javascript_Core/offlineasm/arm64.rb 2019-01-21 20:15:53 UTC (rev 240240)
+++ trunk/Source/_javascript_Core/offlineasm/arm64.rb 2019-01-21 20:50:59 UTC (rev 240241)
@@ -460,8 +460,8 @@
raise unless operands[2].register?
if operands[0].immediate?
- if operands[0].value == 0 and flag !~ /s$/
- unless operands[1] == operands[2]
+ if operands[0].value == 0 and opcode !~ /s$/
+ if operands[1] != operands[2]
$asm.puts "mov #{arm64FlippedOperands(operands[1..2], kind)}"
end
else
@@ -496,6 +496,30 @@
$asm.puts "madd #{arm64TACOperands(operands, kind)}, #{arm64GPRName('xzr', kind)}"
end
+def emitARM64Sub(opcode, operands, kind)
+ if operands.size == 3
+ raise unless operands[0].register?
+ raise unless operands[2].register?
+
+ if operands[1].immediate?
+ if operands[1].value == 0 and opcode !~ /s$/
+ if operands[0] != operands[2]
+ $asm.puts "mov #{arm64FlippedOperands([operands[0], operands[2]], kind)}"
+ end
+ return
+ end
+ end
+ end
+
+ if operands.size == 2
+ if operands[0].immediate? and operands[0].value == 0 and opcode !~ /s$/
+ return
+ end
+ end
+
+ emitARM64TAC(opcode, operands, kind)
+end
+
def emitARM64Unflipped(opcode, operands, kind)
$asm.puts "#{opcode} #{arm64Operands(operands, kind)}"
end
@@ -655,13 +679,13 @@
when "mulq"
emitARM64Mul('mul', operands, :quad)
when "subi"
- emitARM64TAC("sub", operands, :word)
+ emitARM64Sub("sub", operands, :word)
when "subp"
- emitARM64TAC("sub", operands, :ptr)
+ emitARM64Sub("sub", operands, :ptr)
when "subq"
- emitARM64TAC("sub", operands, :quad)
+ emitARM64Sub("sub", operands, :quad)
when "subis"
- emitARM64TAC("subs", operands, :word)
+ emitARM64Sub("subs", operands, :word)
when "negi"
$asm.puts "sub #{operands[0].arm64Operand(:word)}, wzr, #{operands[0].arm64Operand(:word)}"
when "negp"
Modified: trunk/Source/_javascript_Core/offlineasm/x86.rb (240240 => 240241)
--- trunk/Source/_javascript_Core/offlineasm/x86.rb 2019-01-21 20:15:53 UTC (rev 240240)
+++ trunk/Source/_javascript_Core/offlineasm/x86.rb 2019-01-21 20:50:59 UTC (rev 240241)
@@ -761,7 +761,7 @@
raise unless operands[1].is_a? RegisterID
raise unless operands[2].is_a? RegisterID
if operands[0].value == 0
- unless operands[1] == operands[2]
+ if operands[1] != operands[2]
$asm.puts "mov#{x86Suffix(kind)} #{orderOperands(operands[1].x86Operand(kind), operands[2].x86Operand(kind))}"
end
else
@@ -787,12 +787,31 @@
end
def handleX86Sub(kind)
- if operands.size == 3 and operands[1] == operands[2]
- $asm.puts "neg#{x86Suffix(kind)} #{operands[2].x86Operand(kind)}"
- $asm.puts "add#{x86Suffix(kind)} #{orderOperands(operands[0].x86Operand(kind), operands[2].x86Operand(kind))}"
- else
- handleX86Op("sub#{x86Suffix(kind)}", kind)
+ if operands.size == 3
+ if Immediate.new(nil, 0) == operands[1]
+ raise unless operands[0].is_a? RegisterID
+ raise unless operands[2].is_a? RegisterID
+ if operands[0] != operands[2]
+ $asm.puts "mov#{x86Suffix(kind)} #{orderOperands(operands[0].x86Operand(kind), operands[2].x86Operand(kind))}"
+ end
+ return
+ end
+ if operands[1] == operands[2]
+ $asm.puts "neg#{x86Suffix(kind)} #{operands[2].x86Operand(kind)}"
+ if Immediate.new(nil, 0) != operands[0]
+ $asm.puts "add#{x86Suffix(kind)} #{orderOperands(operands[0].x86Operand(kind), operands[2].x86Operand(kind))}"
+ end
+ return
+ end
end
+
+ if operands.size == 2
+ if Immediate.new(nil, 0) == operands[0]
+ return
+ end
+ end
+
+ handleX86Op("sub#{x86Suffix(kind)}", kind)
end
def handleX86Mul(kind)
