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refactor: always use the highest address of the stack for the probe #32

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Merged
lufia merged 1 commit into from
Aug 22, 2026
Merged

refactor: always use the highest address of the stack for the probe #32

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5 changes: 2 additions & 3 deletions asm_386.s
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,9 @@ TEXT ·raise(SB),NOSPLIT|NOFRAME,$0
MOVB $1, ret+4(FP)
RET

// returns stack-top
TEXT ·getbp(SB),NOSPLIT|NOFRAME,$0
TEXT ·stkhi(SB),NOSPLIT|NOFRAME,$0
NO_LOCAL_POINTERS
MOVL (TLS), DI
MOVL (g_stack+stack_hi)(DI), AX // g.stack.hi -> AX
MOVL AX, ret+4(FP)
MOVL AX, ret+0(FP)
RET
16 changes: 4 additions & 12 deletions asm_amd64.s
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Expand Up @@ -10,7 +10,7 @@ TEXT ·waserror(SB),NOSPLIT|NOFRAME,$0
MOVQ DX, Checkpoint_ctxt(DI)
MOVQ (SP), AX
MOVQ AX, Checkpoint_pc(DI)
MOVQ (BP), AX
MOVQ (g_stack+stack_hi)(R14), AX // g.stack.hi -> AX
MOVQ AX, Checkpoint_probe(DI)
MOVB $0, ret+8(FP)
RET
Expand All @@ -26,16 +26,8 @@ TEXT ·raise(SB),NOSPLIT|NOFRAME,$0
MOVB $1, ret+8(FP)
RET

TEXT ·getbp(SB),NOSPLIT|NOFRAME,$0
TEXT ·stkhi(SB),NOSPLIT|NOFRAME,$0
NO_LOCAL_POINTERS
MOVQ skip+0(FP), DI
MOVQ BP, AX
loop:
CMPQ DI, $0
JBE end
MOVQ (AX), AX
DECQ DI
JMP loop
end:
MOVQ AX, ret+8(FP)
MOVQ (g_stack+stack_hi)(R14), AX // g.stack.hi -> AX
MOVQ AX, ret+0(FP)
RET
16 changes: 4 additions & 12 deletions asm_arm64.s
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Expand Up @@ -10,7 +10,7 @@ TEXT ·waserror(SB),NOSPLIT|NOFRAME,$0
MOVD R29, Checkpoint_bp(R2)
MOVD R26, Checkpoint_ctxt(R2)
MOVD LR, Checkpoint_pc(R2)
MOVD (R29), R0
MOVD (g_stack+stack_hi)(g), R0 // g.stack.hi -> R0
MOVD R0, Checkpoint_probe(R2)
MOVD $0, R0
MOVD R0, ret+8(FP)
Expand All @@ -28,16 +28,8 @@ TEXT ·raise(SB),NOSPLIT|NOFRAME,$0
MOVD R0, ret+8(FP)
RET

TEXT ·getbp(SB),NOSPLIT|NOFRAME,$0
TEXT ·stkhi(SB),NOSPLIT|NOFRAME,$0
NO_LOCAL_POINTERS
MOVD skip+0(FP), R2
MOVD R29, R0
loop:
CMP $0, R2 // 0 > R2
BLE end
MOVD (R0), R0
SUB $1, R2, R2
JMP loop
end:
MOVD R0, ret+8(FP)
MOVD (g_stack+stack_hi)(g), R0 // g.stack.hi -> R0
MOVD R0, ret+0(FP)
RET
6 changes: 3 additions & 3 deletions try.go
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Expand Up @@ -57,7 +57,7 @@ func WithIgnore(errs ...error) Option {

func waserror(cp *Checkpoint) bool
func raise(cp *Checkpoint) bool
func getbp(skip int) uintptr
func stkhi() uintptr

// Handle creates a fallback point.
func Handle() (*Checkpoint, error) {
Expand All @@ -80,8 +80,8 @@ func (cp *Checkpoint) raise(skip int, err error) {
}
cp.err = err

bp := getbp(skip + 1)
d := bp - cp.probe
hi := stkhi()
d := hi - cp.probe
cp.probe += d
cp.sp += d
cp.bp += d
Expand Down
12 changes: 6 additions & 6 deletions try_test.go
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Expand Up @@ -10,16 +10,16 @@ import (
)

func TestBP(t *testing.T) {
bp0 := getbp(1)
bp1 := wrap(2)
if bp0 != bp1 {
t.Errorf("bp0 = 0x%x; bp1 = 0x%x\n", bp0, bp1)
p1 := stkhi()
p2 := wrapstkhi()
if p1 != p2 {
t.Errorf("p1 = 0x%x; p2 = 0x%x\n", p1, p2)
}
}

//go:noinline
func wrap(skip int) uintptr {
return getbp(skip)
func wrapstkhi() uintptr {
return stkhi()
}

func TestHandle(t *testing.T) {
Expand Down