- Revision
- 294768
- Author
- [email protected]
- Date
- 2022-05-24 14:55:45 -0700 (Tue, 24 May 2022)
Log Message
Use the Clang .alt_entry directive to allow use of global labels in LLInt asm.
https://bugs.webkit.org/show_bug.cgi?id=240881
Reviewed by Geoffrey Garen.
With this, debugging LLInt code will be easier. LLInt code will no longer all be at an
offset from vmEntryToJavaScript. They will instead be broken up into different sections
under human readable labels.
Secondly, crash traces of LLInt crashes will now be able to give us the nearest label
for a crash site, as opposed to everything being an offset from vmEntryToJavaScript.
For example, instead of this:
_javascript_Core`vmEntryToJavaScript:
0x1026525b8 <+0>: pacibsp
0x1026525bc <+4>: stp x29, x30, [sp, #-0x10]!
0x1026525c0 <+8>: mov x29, sp
0x1026525c4 <+12>: sub sp, x29, #0xb0
0x1026525c8 <+16>: mov x13, #0xc800
0x1026525cc <+20>: add x17, x1, x13
0x1026525d0 <+24>: ldr w4, [x17]
0x1026525d4 <+28>: cbnz w4, 0x10265275c ; vmEntryToJavaScriptGateAfter + 120
0x1026525d8 <+32>: str x1, [sp]
0x1026525dc <+36>: mov x17, #0x9e78
0x1026525e0 <+40>: add x13, x1, x17
0x1026525e4 <+44>: ldr x4, [x13]
0x1026525e8 <+48>: str x4, [sp, #0x8]
0x1026525ec <+52>: mov x13, #0x9e70
0x1026525f0 <+56>: add x17, x1, x13
0x1026525f4 <+60>: ldr x4, [x17]
0x1026525f8 <+64>: str x4, [sp, #0x10]
0x1026525fc <+68>: ldr x4, [x2, #0x8]
0x102652600 <+72>: str x4, [sp, #0x18]
0x102652604 <+76>: ldr w4, [x2, #0x20]
0x102652608 <+80>: add x4, x4, #0x5
0x10265260c <+84>: lsl x4, x4, #3
0x102652610 <+88>: sub x3, sp, x4
0x102652614 <+92>: cmp sp, x3
0x102652618 <+96>: b.ls 0x10265271c ; vmEntryToJavaScriptGateAfter + 56
0x10265261c <+100>: mov x17, #0xca00
0x102652620 <+104>: add x13, x1, x17
0x102652624 <+108>: ldr x17, [x13]
0x102652628 <+112>: cmp x3, x17
0x10265262c <+116>: b.lo 0x10265271c ; vmEntryToJavaScriptGateAfter + 56
0x102652630 <+120>: mov sp, x3
0x102652634 <+124>: mov x3, #0x4
0x102652638 <+128>: sub w3, w3, #0x1
0x10265263c <+132>: add x17, x2, x3, lsl #3
0x102652640 <+136>: ldr x5, [x17]
We now get this:
_javascript_Core`vmEntryToJavaScript:
0x1028b5d90 <+0>: pacibsp
0x1028b5d94 <+4>: stp x29, x30, [sp, #-0x10]!
0x1028b5d98 <+8>: mov x29, sp
0x1028b5d9c <+12>: sub sp, x29, #0xb0
0x1028b5da0 <+16>: mov x13, #0xc800
0x1028b5da4 <+20>: add x17, x1, x13
0x1028b5da8 <+24>: ldr w4, [x17]
0x1028b5dac <+28>: cbnz w4, 0x1028b5f34 ; _offlineasm_doVMEntry__checkVMEntryPermission
0x1028b5db0 <+32>: str x1, [sp]
0x1028b5db4 <+36>: mov x17, #0x9e78
0x1028b5db8 <+40>: add x13, x1, x17
0x1028b5dbc <+44>: ldr x4, [x13]
0x1028b5dc0 <+48>: str x4, [sp, #0x8]
0x1028b5dc4 <+52>: mov x13, #0x9e70
0x1028b5dc8 <+56>: add x17, x1, x13
0x1028b5dcc <+60>: ldr x4, [x17]
0x1028b5dd0 <+64>: str x4, [sp, #0x10]
0x1028b5dd4 <+68>: ldr x4, [x2, #0x8]
0x1028b5dd8 <+72>: str x4, [sp, #0x18]
0x1028b5ddc <+76>: ldr w4, [x2, #0x20]
0x1028b5de0 <+80>: add x4, x4, #0x5
0x1028b5de4 <+84>: lsl x4, x4, #3
0x1028b5de8 <+88>: sub x3, sp, x4
0x1028b5dec <+92>: cmp sp, x3
0x1028b5df0 <+96>: b.ls 0x1028b5ef4 ; _offlineasm_doVMEntry__throwStackOverflow
0x1028b5df4 <+100>: mov x17, #0xca00
0x1028b5df8 <+104>: add x13, x1, x17
0x1028b5dfc <+108>: ldr x17, [x13]
0x1028b5e00 <+112>: cmp x3, x17
0x1028b5e04 <+116>: b.lo 0x1028b5ef4 ; _offlineasm_doVMEntry__throwStackOverflow
_javascript_Core`_offlineasm_doVMEntry__stackHeightOK:
0x1028b5e08 <+0>: mov sp, x3
0x1028b5e0c <+4>: mov x3, #0x4
_javascript_Core`_offlineasm_doVMEntry__copyHeaderLoop:
0x1028b5e10 <+0>: sub w3, w3, #0x1
0x1028b5e14 <+4>: add x17, x2, x3, lsl #3
0x1028b5e18 <+8>: ldr x5, [x17]
This feature is only available when COMPILER(CLANG) is true.
* Source/_javascript_Core/llint/LowLevelInterpreter.cpp:
Canonical link: https://commits.webkit.org/250933@main
Modified Paths
