runtime: fix arm5 softfloat

R=dfc, ken2, rsc
CC=golang-dev
https://golang.org/cl/4446043

diff --git a/src/pkg/runtime/arm/softfloat.c b/src/pkg/runtime/arm/softfloat.c
index f60fab14f40c9fa002d425f0930f06583bf0d944..f91a6fc09b73f0756147d436ecb7fcbaa46f66e4 100644 (file)
--- a/src/pkg/runtime/arm/softfloat.c
+++ b/src/pkg/runtime/arm/softfloat.c
@@ -91,6 +91,7 @@ static uint32
 stepflt(uint32 *pc, uint32 *regs)
 {
        uint32 i, regd, regm, regn;
+       int32 delta;
        uint32 *addr;
        uint64 uval;
        int64 sval;
@@ -117,7 +118,7 @@ stepflt(uint32 *pc, uint32 *regs)
                return 1;
        }
        if(i == 0xe08bb00d) {
-               // add sp to 11.
+               // add sp to r11.
                // might be part of a large stack offset address
                // (or might not, but again no harm done).
                regs[11] += regs[13];
@@ -134,6 +135,19 @@ stepflt(uint32 *pc, uint32 *regs)
                        runtime·printf("*** fpsr R[CPSR] = F[CPSR] %x\n", regs[CPSR]);
                return 1;
        }
+       if((i&0xff000000) == 0xea000000) {
+               // unconditional branch
+               // can happen in the middle of floating point
+               // if the linker decides it is time to lay down
+               // a sequence of instruction stream constants.
+               delta = i&0xffffff;
+               delta = (delta<<8) >> 8;        // sign extend
+
+               if(trace)
+                       runtime·printf("*** cpu PC += %x\n", (delta+2)*4);
+               return delta+2;
+       }
+
        goto stage1;
 
 stage1:        // load/store regn is cpureg, regm is 8bit offset
@@ -489,8 +503,10 @@ runtime·_sfloat2(uint32 *lr, uint32 r0)
        uint32 skip;
 
        skip = stepflt(lr, &r0);
-       if(skip == 0)
+       if(skip == 0) {
+               runtime·printf("sfloat2 %p %x\n", lr, *lr);
                fabort(); // not ok to fail first instruction
+       }
 
        lr += skip;
        while(skip = stepflt(lr, &r0))