Bug 175512 – [ARM64] Use x29 and x30 instead of fp and lr to make GCC happy

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Mark Lam]

This is needed because Linux toolchains are not smart enough to resolve constexpr numeric expressions.  See https://bugs.webkit.org/show_bug.cgi?id=175446#c21.

[Radar WebKit Bug Importer]

<rdar://problem/33863584>

[Mark Lam]

Also need to add MacroAssemblerARM64.cpp to the JSC CMakeList.txt.

[Mark Lam]

Created attachment 317997 [details]
proposed patch.

[Mark Lam]

@Ossy, this patch works for OS(DARWIN) with Clang.  Can you please verify that this resolves the issue you reported in https://bugs.webkit.org/show_bug.cgi?id=175446#c21 ?

[Csaba Osztrogonác]

(In reply to Mark Lam from comment #4)
> @Ossy, this patch works for OS(DARWIN) with Clang.  Can you please verify
> that this resolves the issue you reported in
> https://bugs.webkit.org/show_bug.cgi?id=175446#c21 ?

Thanks for the quick fix, I'll run a build and test soon.

[Csaba Osztrogonác]

Now I got these errors:

{standard input}: Assembler messages:
{standard input}:34: Error: operand 2 should be an integer register -- `stp x28,fp,[sp,#240]'
{standard input}:37: Error: operand 1 should be an integer register -- `str lr,[sp,#552]'
{standard input}:38: Error: operand 1 should be an integer or stack pointer register -- `add lr,lr,#2*8'
{standard input}:39: Error: operand 1 should be an integer register -- `str lr,[sp,#272]'
{standard input}:94: Error: operand 1 should be an integer register -- `mov lr,#0'
{standard input}:104: Error: operand 1 should be an integer register -- `mov lr,#1'
{standard input}:106: Error: operand 1 should be an integer register -- `ldr fp,[sp,#552]'
{standard input}:114: Error: operand 1 should be an integer register -- `str lr,[sp,#16]'
{standard input}:115: Error: operand 2 should be an integer register -- `ldp x28,lr,[x27,#232]'
{standard input}:116: Error: operand 2 should be an integer register -- `stp x28,lr,[sp,#232]'
{standard input}:117: Error: operand 2 should be an integer register -- `ldp x28,lr,[x27,#248]'
{standard input}:118: Error: operand 2 should be an integer register -- `stp x28,lr,[sp,#248]'
{standard input}:119: Error: operand 2 should be an integer register -- `ldp x28,lr,[x27,#264]'
{standard input}:120: Error: operand 2 should be an integer register -- `stp x28,lr,[sp,#264]'
{standard input}:121: Error: operand 2 should be an integer register -- `ldp x28,lr,[x27,#280]'
{standard input}:122: Error: operand 2 should be an integer register -- `stp x28,lr,[sp,#280]'
{standard input}:123: Error: operand 1 should be an integer register -- `ldr lr,[sp,#16]'
{standard input}:125: Error: operand 1 should be an integer register -- `cbnz lr,.LctiMasmProbeTrampolineEnd'
{standard input}:126: Error: operand 1 should be an integer register -- `ldr lr,[sp,#264]'
{standard input}:127: Error: operand 1 should be an integer or stack pointer register -- `sub lr,lr,#(6*8)'
{standard input}:129: Error: integer 64-bit register expected at operand 2 -- `str x27,[lr,#(5*8)]'
{standard input}:130: Error: operand 1 should be an integer register -- `str lr,[sp,#264]'
{standard input}:131: Error: operand 1 should be an integer register -- `str fp,[sp,#272]'
{standard input}:133: Error: operand 1 should be an integer register -- `ldr lr,[sp,#264]'
{standard input}:134: Error: operand 1 should be an integer or stack pointer register -- `sub lr,lr,#(6*8)'
{standard input}:136: Error: integer 64-bit register expected at operand 3 -- `stp x27,x28,[lr,#(0*8)]'
{standard input}:138: Error: integer 64-bit register expected at operand 3 -- `stp x27,x28,[lr,#(2*8)]'
{standard input}:141: Error: integer 64-bit register expected at operand 3 -- `stp x27,x28,[lr,#(4*8)]'
{standard input}:147: Error: operand 1 should be a floating-point register -- `ldp fp,lr,[sp],#2*8'

[Csaba Osztrogonác]

I checked it in details, it seems not the constexprs were the problem,
but fp and lr names. Replacing them with x29 and x30 made GCC happy.
I'll run tests and will upload a fix if everything is OK.

[Csaba Osztrogonác]

Created attachment 318001 [details]
Patch

[Mark Lam]

Comment on attachment 318001 [details]
Patch

r=me.  Please put a comment in ctiMasmProbeTrampoline to explain that why we're using x29 and x30, something like: "We use x29 and x30 instead of fp and lr because gcc's inline assembler does not recognize fp and lr."  This will minimize the chance that someone will change them back to sp and lr at a later date unknowingly.

[Csaba Osztrogonác]

Created attachment 318005 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 318005 [details]
Patch for landing

Clearing flags on attachment: 318005

Committed r220630: <http://trac.webkit.org/changeset/220630>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.