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 61cd36550ba1ea04273451c968ed8aae6d835080..e932750b54aa64ed6c59740bf35e14cf813d687c 100644 (file)
--- a/src/cmd/5l/noop.c
+++ b/src/cmd/5l/noop.c
@@ -128,7 +128,7 @@ noops(void)
        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 @@ noops(void)
                                // 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 @@ noops(void)
                                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 = 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;
+                               p->from.offset = (curtext->to.offset2 & ~7) + 4;
                                p->to.type = D_REG;
                                p->to.reg = 2;
 
@@ -401,7 +412,7 @@ noops(void)
                                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 aa21ab8506862331d9ed936abb914adcf22366c8..98c9e06bf5270138adcc4e1825c8d37cc339f171 100644 (file)
--- a/src/pkg/runtime/arm/asm.s
+++ b/src/pkg/runtime/arm/asm.s
@@ -120,7 +120,6 @@ TEXT gogocall(SB), 7, $-4
        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 @@ TEXT gogocall(SB), 7, $-4
 // 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 @@ TEXT runtime·morestack(SB),7,$-4
        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 @@ TEXT reflect·call(SB), 7, $-4
        // 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 @@ TEXT runtime·lessstack(SB), 7, $-4
        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 fac0008ee10705032255d381738592c360954a70..068e2bea14983f17f1ea8fd79c8992e28633e914 100644 (file)
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -152,7 +152,6 @@ struct      Gobuf
        byte*   sp;
        byte*   pc;
        G*      g;
-       uintptr r0;             // used on arm
 };
 struct G
 {