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42b0e9f253
This change reduces the binary size on macOS x64 by around 50KB.
Here's a diff of the impact on the code generated for Attr_Binding::get_specified
in the Mac build. It's a bit hard to read because %r12 and %rbx swap their
function, but what happens in this method is that "movq %r12, %rcx" goes
away, and the two instructions "leal 0x1(%r12) %eax" and
"movl %eax, 0x10(%rbx)" turn into an "incl 0x10(%r12)".
So the old code was preserving the original value of profilingStack->stackPointer
in a register, and then using it later to compute the incremented stackPointer.
The new code uses an "incl" instruction for the stackPointer increment and
doesn't worry that the stackPointer value might have changed since the stack
size check at the start of the function. (It can't have changed.)
before: %rbx has the ProfilingStack*, %r12 has profilingStack->stackPointer
after: %r12 has the ProfilingStack*, %rbx has profilingStack->stackPointer
@@ -3,37 +3,35 @@
movq %rsp, %rbp
pushq %r15
pushq %r14
pushq %r12
pushq %rbx
subq $0x10, %rsp
movq %rcx, %r14
movq %rdx, %r15
- movq 0x80(%rdi), %rbx
- movq %rbx, -40(%rbp)
- testq %rbx, %rbx
+ movq 0x80(%rdi), %r12
+ movq %r12, -40(%rbp)
+ testq %r12, %r12
je loc_xxxxx
- movl 0x10(%rbx), %r12d
- cmpl (%rbx), %r12d
+ movl 0x10(%r12), %ebx
+ cmpl (%r12), %ebx
jae loc_xxxxx
- movq 0x8(%rbx), %rax
- movq %r12, %rcx
- shlq $0x5, %rcx
- leaq aAttr, %rdx ; "Attr"
- movq %rdx, (%rax,%rcx)
- leaq aSpecified, %rdx ; "specified"
- movq %rdx, 0x8(%rax,%rcx)
- leaq -40(%rbp), %rdx
- movq %rdx, 0x10(%rax,%rcx)
- movl $0x3a1, 0x1c(%rax,%rcx)
- leal 0x1(%r12), %eax
- movl %eax, 0x10(%rbx)
+ movq 0x8(%r12), %rax
+ shlq $0x5, %rbx
+ leaq aAttr, %rcx ; "Attr"
+ movq %rcx, (%rax,%rbx)
+ leaq aSpecified, %rcx ; "specified"
+ movq %rcx, 0x8(%rax,%rbx)
+ leaq -40(%rbp), %rcx
+ movq %rcx, 0x10(%rax,%rbx)
+ movl $0x3a1, 0x1c(%rax,%rbx)
+ incl 0x10(%r12)
movq %r15, %rdi
call __ZNK7mozilla3dom4Attr9SpecifiedEv ; mozilla::dom::Attr::Specified() const
movzxl %al, %eax
movabsq $0xfff9000000000000, %rcx
orq %rax, %rcx
movq %rcx, (%r14)
movq -40(%rbp), %rax
@@ -47,11 +45,11 @@
popq %rbx
popq %r12
popq %r14
popq %r15
popq %rbp
ret
; endp
- movq %rbx, %rdi
+ movq %r12, %rdi
call __ZN14ProfilingStack18ensureCapacitySlowEv ; ProfilingStack::ensureCapacitySlow()
jmp loc_xxxxx
Depends on D9205
Differential Revision: https://phabricator.services.mozilla.com/D9206
--HG--
extra : moz-landing-system : lando
|
||
|---|---|---|
| .. | ||
| AllocPolicy.h | ||
| CallArgs.h | ||
| CallNonGenericMethod.h | ||
| CharacterEncoding.h | ||
| Class.h | ||
| CompilationAndEvaluation.h | ||
| CompileOptions.h | ||
| Conversions.h | ||
| Date.h | ||
| Debug.h | ||
| ErrorReport.h | ||
| GCAnnotations.h | ||
| GCAPI.h | ||
| GCHashTable.h | ||
| GCPolicyAPI.h | ||
| GCVariant.h | ||
| GCVector.h | ||
| HashTable.h | ||
| HeapAPI.h | ||
| Id.h | ||
| Initialization.h | ||
| JSON.h | ||
| LocaleSensitive.h | ||
| MemoryFunctions.h | ||
| MemoryMetrics.h | ||
| OffThreadScriptCompilation.h | ||
| Principals.h | ||
| Printf.h | ||
| ProfilingFrameIterator.h | ||
| ProfilingStack.h | ||
| ProtoKey.h | ||
| Proxy.h | ||
| Realm.h | ||
| RefCounted.h | ||
| RequiredDefines.h | ||
| Result.h | ||
| RootingAPI.h | ||
| SavedFrameAPI.h | ||
| SliceBudget.h | ||
| SourceBufferHolder.h | ||
| StableStringChars.h | ||
| Stream.h | ||
| StructuredClone.h | ||
| SweepingAPI.h | ||
| TraceKind.h | ||
| TraceLoggerAPI.h | ||
| TracingAPI.h | ||
| TrackedOptimizationInfo.h | ||
| Transcoding.h | ||
| TypeDecls.h | ||
| UbiNode.h | ||
| UbiNodeBreadthFirst.h | ||
| UbiNodeCensus.h | ||
| UbiNodeDominatorTree.h | ||
| UbiNodePostOrder.h | ||
| UbiNodeShortestPaths.h | ||
| UbiNodeUtils.h | ||
| UniquePtr.h | ||
| Utility.h | ||
| Value.h | ||
| Vector.h | ||
| WeakMapPtr.h | ||
| Wrapper.h | ||