[libunwind] [Mips] Fixed libunwind::Registers_mips_o32::jumpto to allow for load delay (PR #152942)
via cfe-commits
cfe-commits at lists.llvm.org
Sun Aug 10 14:55:46 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libunwind
Author: Jade Marker (Jade-Marker)
<details>
<summary>Changes</summary>
Fix #<!-- -->152922
Note: I'm unsure if this is necessary on mips64, I've added it for good measure though
---
Full diff: https://github.com/llvm/llvm-project/pull/152942.diff
1 Files Affected:
- (modified) libunwind/src/UnwindRegistersRestore.S (+6-3)
``````````diff
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S
index 5e199188945df..2b1593b16754e 100644
--- a/libunwind/src/UnwindRegistersRestore.S
+++ b/libunwind/src/UnwindRegistersRestore.S
@@ -1044,9 +1044,10 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind18Registers_mips_o326jumptoEv)
lw $27, (4 * 27)($4)
lw $28, (4 * 28)($4)
lw $29, (4 * 29)($4)
- lw $30, (4 * 30)($4)
// load new pc into ra
lw $31, (4 * 32)($4)
+ //allow for load delay, so that ra address is new value when jumping
+ lw $30, (4 * 30)($4)
// jump to ra, load a0 in the delay slot
jr $31
lw $4, (4 * 4)($4)
@@ -1082,11 +1083,13 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind21Registers_mips_newabi6jumptoEv)
ld $2, (8 * 2)($4)
ld $3, (8 * 3)($4)
// skip a0 for now
- .irp i,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
+ .irp i,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
ld $\i, (8 * \i)($4)
.endr
// load new pc into ra
- ld $31, (8 * 32)($4)
+ ld $31, (4 * 32)($4)
+ //allow for load delay, so that ra address is new value when jumping
+ ld $30, (4 * 30)($4)
// jump to ra, load a0 in the delay slot
jr $31
ld $4, (8 * 4)($4)
``````````
</details>
https://github.com/llvm/llvm-project/pull/152942
More information about the cfe-commits
mailing list