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[release-branch.go1] runtime: support conditional execution in ARM softfloat

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««« backport 87ef5e0baaf5
runtime: support conditional execution in ARM softfloat
        Fixes #3638.

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6213057

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This commit is contained in:
Shenghou Ma 2012-06-13 16:24:08 -04:00
parent b503008c9d
commit adb732b5fd
1 changed files with 59 additions and 6 deletions
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65
src/pkg/runtime/softfloat_arm.c
View File

@ -9,10 +9,10 @@
#include "runtime.h"
#define CPSR 14
#define FLAGS_N (1 << 31)
#define FLAGS_Z (1 << 30)
#define FLAGS_C (1 << 29)
#define FLAGS_V (1 << 28)
#define FLAGS_N (1U << 31)
#define FLAGS_Z (1U << 30)
#define FLAGS_C (1U << 29)
#define FLAGS_V (1U << 28)
void runtime·abort(void);
void math·sqrtC(uint64, uint64*);
@ -86,12 +86,24 @@ fstatus(bool nan, int32 cmp)
return FLAGS_C;
}
// conditions array record the required CPSR cond field for the
// first 5 pairs of conditional execution opcodes
// higher 4 bits are must set, lower 4 bits are must clear
static const uint8 conditions[10/2] = {
[0/2] = (FLAGS_Z >> 24) | 0, // 0: EQ (Z set), 1: NE (Z clear)
[2/2] = (FLAGS_C >> 24) | 0, // 2: CS/HS (C set), 3: CC/LO (C clear)
[4/2] = (FLAGS_N >> 24) | 0, // 4: MI (N set), 5: PL (N clear)
[6/2] = (FLAGS_V >> 24) | 0, // 6: VS (V set), 7: VC (V clear)
[8/2] = (FLAGS_C >> 24) |
(FLAGS_Z >> 28), // 8: HI (C set and Z clear), 9: LS (C clear and Z set)
};
// returns number of words that the fp instruction
// is occupying, 0 if next instruction isn't float.
static uint32
stepflt(uint32 *pc, uint32 *regs)
{
uint32 i, regd, regm, regn;
uint32 i, opc, regd, regm, regn, cpsr;
int32 delta;
uint32 *addr;
uint64 uval;
@ -102,8 +114,49 @@ stepflt(uint32 *pc, uint32 *regs)
i = *pc;
if(trace)
runtime·printf("stepflt %p %x\n", pc, i);
runtime·printf("stepflt %p %x (cpsr %x)\n", pc, i, regs[CPSR] >> 28);
opc = i >> 28;
if(opc == 14) // common case first
goto execute;
cpsr = regs[CPSR] >> 28;
switch(opc) {
case 0: case 1: case 2: case 3: case 4:
case 5: case 6: case 7: case 8: case 9:
if(((cpsr & (conditions[opc/2] >> 4)) == (conditions[opc/2] >> 4)) &&
((cpsr & (conditions[opc/2] & 0xf)) == 0)) {
if(opc & 1) return 1;
} else {
if(!(opc & 1)) return 1;
}
break;
case 10: // GE (N == V)
case 11: // LT (N != V)
if((cpsr & (FLAGS_N >> 28)) == (cpsr & (FLAGS_V >> 28))) {
if(opc & 1) return 1;
} else {
if(!(opc & 1)) return 1;
}
break;
case 12: // GT (N == V and Z == 0)
case 13: // LE (N != V or Z == 1)
if((cpsr & (FLAGS_N >> 28)) == (cpsr & (FLAGS_V >> 28)) &&
(cpsr & (FLAGS_Z >> 28)) == 0) {
if(opc & 1) return 1;
} else {
if(!(opc & 1)) return 1;
}
break;
case 14: // AL
break;
case 15: // shouldn't happen
return 0;
}
if(trace)
runtime·printf("conditional %x (cpsr %x) pass\n", opc, cpsr);
i = (0xeU << 28) | (i & 0xfffffff);
execute:
// special cases
if((i&0xfffff000) == 0xe59fb000) {
// load r11 from pc-relative address.