fix off by 4 bug in morestack (lr again). remove storing of r0
now that all arguments are passed on the stack.
go/test: passes 89% (310/345)
R=rsc
APPROVED=rsc
DELTA=33 (13 added, 14 deleted, 6 changed)
OCL=36009
CL=36022
diff --git a/src/cmd/5l/noop.c b/src/cmd/5l/noop.c
index 61cd365..e932750 100644
--- a/src/cmd/5l/noop.c
+++ b/src/cmd/5l/noop.c
@@ -128,7 +128,7 @@
Bflush(&bso);
pmorestack = P;
- symmorestack = lookup("runtime·morestackx", 0);
+ symmorestack = lookup("runtime·morestack", 0);
if(symmorestack->type == STEXT)
for(p = firstp; p != P; p = p->link) {
@@ -358,9 +358,10 @@
// split stack check for small functions
// MOVW g_stackguard(g), R1
// CMP R1, $-autosize(SP)
+ // MOVW.LO $autosize, R1
// MOVW.LO $args, R2
- // MOVW.W.LO R14, R3
- // BL.LO runtime·morestackx(SB) // modifies LR
+ // MOVW.W.LO R14, R3
+ // BL.LO runtime·morestack(SB) // modifies LR
// MOVW.W R14,$-autosize(SP)
// TODO(kaib): add more trampolines
@@ -383,12 +384,22 @@
p->from.offset = -autosize;
p->reg = REGSP;
- // MOVW.LO $args, R2
+ // MOVW.LO $autosize, R1
p = appendp(p);
p->as = AMOVW;
p->scond = C_SCOND_LO;
p->from.type = D_CONST;
- p->from.offset = curtext->to.offset2 & ~7;
+ p->from.offset = 0;
+ p->to.type = D_REG;
+ p->to.reg = 1;
+
+ // MOVW.LO $args +4, R2
+ // also need to store the extra 4 bytes.
+ p = appendp(p);
+ p->as = AMOVW;
+ p->scond = C_SCOND_LO;
+ p->from.type = D_CONST;
+ p->from.offset = (curtext->to.offset2 & ~7) + 4;
p->to.type = D_REG;
p->to.reg = 2;
@@ -401,7 +412,7 @@
p->to.type = D_REG;
p->to.reg = 3;
- // BL.LO runtime·morestackx(SB) // modifies LR
+ // BL.LO runtime·morestack(SB) // modifies LR
p = appendp(p);
p->as = ABL;
p->scond = C_SCOND_LO;
diff --git a/src/pkg/runtime/arm/asm.s b/src/pkg/runtime/arm/asm.s
index aa21ab8..98c9e06 100644
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/arm/asm.s
@@ -120,7 +120,6 @@
MOVW 0(g), R2 // make sure g != nil
MOVW gobuf_sp(R0), SP // restore SP
MOVW gobuf_pc(R0), LR
- MOVW gobuf_r0(R0), R0
MOVW R1, PC
/*
@@ -131,6 +130,8 @@
// R1 frame size
// R2 arg size
// R3 prolog's LR
+// NB. we do not save R0 because the we've forced 5c to pass all arguments
+// on the stack.
// using frame size $-4 means do not save LR on stack.
TEXT runtime·morestack(SB),7,$-4
// Cannot grow scheduler stack (m->g0).
@@ -149,7 +150,6 @@
MOVW SP, (m_morebuf+gobuf_sp)(m) // f's caller's SP
MOVW SP, m_morefp(m) // f's caller's SP
MOVW g, (m_morebuf+gobuf_g)(m)
- MOVW R0, (m_morebuf+gobuf_r0)(m)
// Set m->morepc to f's PC.
MOVW LR, m_morepc(m)
@@ -169,7 +169,6 @@
// restore when returning from f.
MOVW LR, (m_morebuf+gobuf_pc)(m) // our caller's PC
MOVW SP, (m_morebuf+gobuf_sp)(m) // our caller's SP
- MOVW R0, (m_morebuf+gobuf_r0)(m)
MOVW g, (m_morebuf+gobuf_g)(m)
// Set up morestack arguments to call f on a new stack.
@@ -204,16 +203,6 @@
MOVW (m_sched+gobuf_sp)(m), SP
B oldstack(SB)
-// Optimization to make inline stack splitting code smaller
-// R0 is original first argument
-// R2 is argsize
-// R3 is LR for f (f's caller's PC)
-// using frame size $-4 means do not save LR on stack.
-TEXT runtime·morestackx(SB), 7, $-4
- MOVW $0, R1 // set frame size
- B runtime·morestack(SB)
-
-
// void jmpdefer(fn, sp);
// called from deferreturn.
// 1. grab stored LR for caller
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index fac0008..068e2be 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -152,7 +152,6 @@
byte* sp;
byte* pc;
G* g;
- uintptr r0; // used on arm
};
struct G
{
