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go/src/runtime/softfloat_arm.c
Russ Cox c007ce824d build: move package sources from src/pkg to src 
Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.
2014-09-08 00:08:51 -04:00

688 lines
16 KiB
C
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Software floating point interpretaton of ARM 7500 FP instructions.
// The interpretation is not bit compatible with the 7500.
// It uses true little-endian doubles, while the 7500 used mixed-endian.
#include "runtime.h"
#include "textflag.h"
#define CPSR 14
#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 runtime·sqrtC(uint64, uint64*);
static uint32 trace = 0;
static void
fabort(void)
{
if (1) {
runtime·printf("Unsupported floating point instruction\n");
runtime·abort();
}
}
static void
putf(uint32 reg, uint32 val)
{
g->m->freglo[reg] = val;
}
static void
putd(uint32 reg, uint64 val)
{
g->m->freglo[reg] = (uint32)val;
g->m->freghi[reg] = (uint32)(val>>32);
}
static uint64
getd(uint32 reg)
{
return (uint64)g->m->freglo[reg] | ((uint64)g->m->freghi[reg]<<32);
}
static void
fprint(void)
{
uint32 i;
for (i = 0; i < 16; i++) {
runtime·printf("\tf%d:\t%X %X\n", i, g->m->freghi[i], g->m->freglo[i]);
}
}
static uint32
d2f(uint64 d)
{
uint32 x;
runtime·f64to32c(d, &x);
return x;
}
static uint64
f2d(uint32 f)
{
uint64 x;
runtime·f32to64c(f, &x);
return x;
}
static uint32
fstatus(bool nan, int32 cmp)
{
if(nan)
return FLAGS_C | FLAGS_V;
if(cmp == 0)
return FLAGS_Z | FLAGS_C;
if(cmp < 0)
return FLAGS_N;
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
#pragma dataflag NOPTR
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)
};
#define FAULT (0x80000000U) // impossible PC offset
// 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, opc, regd, regm, regn, cpsr;
int32 delta;
uint32 *addr;
uint64 uval;
int64 sval;
bool nan, ok;
int32 cmp;
M *m;
// m is locked in vlop_arm.s, so g->m cannot change during this function call,
// so caching it in a local variable is safe.
m = g->m;
i = *pc;
if(trace)
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.
// might be part of a floating point move
// (or might not, but no harm in simulating
// one instruction too many).
addr = (uint32*)((uint8*)pc + (i&0xfff) + 8);
regs[11] = addr[0];
if(trace)
runtime·printf("*** cpu R[%d] = *(%p) %x\n",
11, addr, regs[11]);
return 1;
}
if(i == 0xe08bb00d) {
// 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];
if(trace)
runtime·printf("*** cpu R[%d] += R[%d] %x\n",
11, 13, regs[11]);
return 1;
}
if(i == 0xeef1fa10) {
regs[CPSR] = (regs[CPSR]&0x0fffffff) | m->fflag;
if(trace)
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
regd = i>>12 & 0xf;
regn = i>>16 & 0xf;
regm = (i & 0xff) << 2; // PLUS or MINUS ??
switch(i & 0xfff00f00) {
default:
goto stage2;
case 0xed900a00: // single load
addr = (uint32*)(regs[regn] + regm);
if((uintptr)addr < 4096) {
if(trace)
runtime·printf("*** load @%p => fault\n", addr);
return FAULT;
}
m->freglo[regd] = addr[0];
if(trace)
runtime·printf("*** load F[%d] = %x\n",
regd, m->freglo[regd]);
break;
case 0xed900b00: // double load
addr = (uint32*)(regs[regn] + regm);
if((uintptr)addr < 4096) {
if(trace)
runtime·printf("*** double load @%p => fault\n", addr);
return FAULT;
}
m->freglo[regd] = addr[0];
m->freghi[regd] = addr[1];
if(trace)
runtime·printf("*** load D[%d] = %x-%x\n",
regd, m->freghi[regd], m->freglo[regd]);
break;
case 0xed800a00: // single store
addr = (uint32*)(regs[regn] + regm);
if((uintptr)addr < 4096) {
if(trace)
runtime·printf("*** store @%p => fault\n", addr);
return FAULT;
}
addr[0] = m->freglo[regd];
if(trace)
runtime·printf("*** *(%p) = %x\n",
addr, addr[0]);
break;
case 0xed800b00: // double store
addr = (uint32*)(regs[regn] + regm);
if((uintptr)addr < 4096) {
if(trace)
runtime·printf("*** double store @%p => fault\n", addr);
return FAULT;
}
addr[0] = m->freglo[regd];
addr[1] = m->freghi[regd];
if(trace)
runtime·printf("*** *(%p) = %x-%x\n",
addr, addr[1], addr[0]);
break;
}
return 1;
stage2: // regd, regm, regn are 4bit variables
regm = i>>0 & 0xf;
switch(i & 0xfff00ff0) {
default:
goto stage3;
case 0xf3000110: // veor
m->freglo[regd] = m->freglo[regm]^m->freglo[regn];
m->freghi[regd] = m->freghi[regm]^m->freghi[regn];
if(trace)
runtime·printf("*** veor D[%d] = %x-%x\n",
regd, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb00b00: // D[regd] = const(regn,regm)
regn = (regn<<4) | regm;
regm = 0x40000000UL;
if(regn & 0x80)
regm |= 0x80000000UL;
if(regn & 0x40)
regm ^= 0x7fc00000UL;
regm |= (regn & 0x3f) << 16;
m->freglo[regd] = 0;
m->freghi[regd] = regm;
if(trace)
runtime·printf("*** immed D[%d] = %x-%x\n",
regd, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb00a00: // F[regd] = const(regn,regm)
regn = (regn<<4) | regm;
regm = 0x40000000UL;
if(regn & 0x80)
regm |= 0x80000000UL;
if(regn & 0x40)
regm ^= 0x7e000000UL;
regm |= (regn & 0x3f) << 19;
m->freglo[regd] = regm;
if(trace)
runtime·printf("*** immed D[%d] = %x\n",
regd, m->freglo[regd]);
break;
case 0xee300b00: // D[regd] = D[regn]+D[regm]
runtime·fadd64c(getd(regn), getd(regm), &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** add D[%d] = D[%d]+D[%d] %x-%x\n",
regd, regn, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xee300a00: // F[regd] = F[regn]+F[regm]
runtime·fadd64c(f2d(m->freglo[regn]), f2d(m->freglo[regm]), &uval);
m->freglo[regd] = d2f(uval);
if(trace)
runtime·printf("*** add F[%d] = F[%d]+F[%d] %x\n",
regd, regn, regm, m->freglo[regd]);
break;
case 0xee300b40: // D[regd] = D[regn]-D[regm]
runtime·fsub64c(getd(regn), getd(regm), &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** sub D[%d] = D[%d]-D[%d] %x-%x\n",
regd, regn, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xee300a40: // F[regd] = F[regn]-F[regm]
runtime·fsub64c(f2d(m->freglo[regn]), f2d(m->freglo[regm]), &uval);
m->freglo[regd] = d2f(uval);
if(trace)
runtime·printf("*** sub F[%d] = F[%d]-F[%d] %x\n",
regd, regn, regm, m->freglo[regd]);
break;
case 0xee200b00: // D[regd] = D[regn]*D[regm]
runtime·fmul64c(getd(regn), getd(regm), &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** mul D[%d] = D[%d]*D[%d] %x-%x\n",
regd, regn, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xee200a00: // F[regd] = F[regn]*F[regm]
runtime·fmul64c(f2d(m->freglo[regn]), f2d(m->freglo[regm]), &uval);
m->freglo[regd] = d2f(uval);
if(trace)
runtime·printf("*** mul F[%d] = F[%d]*F[%d] %x\n",
regd, regn, regm, m->freglo[regd]);
break;
case 0xee800b00: // D[regd] = D[regn]/D[regm]
runtime·fdiv64c(getd(regn), getd(regm), &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** div D[%d] = D[%d]/D[%d] %x-%x\n",
regd, regn, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xee800a00: // F[regd] = F[regn]/F[regm]
runtime·fdiv64c(f2d(m->freglo[regn]), f2d(m->freglo[regm]), &uval);
m->freglo[regd] = d2f(uval);
if(trace)
runtime·printf("*** div F[%d] = F[%d]/F[%d] %x\n",
regd, regn, regm, m->freglo[regd]);
break;
case 0xee000b10: // S[regn] = R[regd] (MOVW) (regm ignored)
m->freglo[regn] = regs[regd];
if(trace)
runtime·printf("*** cpy S[%d] = R[%d] %x\n",
regn, regd, m->freglo[regn]);
break;
case 0xee100b10: // R[regd] = S[regn] (MOVW) (regm ignored)
regs[regd] = m->freglo[regn];
if(trace)
runtime·printf("*** cpy R[%d] = S[%d] %x\n",
regd, regn, regs[regd]);
break;
}
return 1;
stage3: // regd, regm are 4bit variables
switch(i & 0xffff0ff0) {
default:
goto done;
case 0xeeb00a40: // F[regd] = F[regm] (MOVF)
m->freglo[regd] = m->freglo[regm];
if(trace)
runtime·printf("*** F[%d] = F[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeeb00b40: // D[regd] = D[regm] (MOVD)
m->freglo[regd] = m->freglo[regm];
m->freghi[regd] = m->freghi[regm];
if(trace)
runtime·printf("*** D[%d] = D[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb10bc0: // D[regd] = sqrt D[regm]
runtime·sqrtC(getd(regm), &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** D[%d] = sqrt D[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb00bc0: // D[regd] = abs D[regm]
m->freglo[regd] = m->freglo[regm];
m->freghi[regd] = m->freghi[regm] & ((1<<31)-1);
if(trace)
runtime·printf("*** D[%d] = abs D[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb00ac0: // F[regd] = abs F[regm]
m->freglo[regd] = m->freglo[regm] & ((1<<31)-1);
if(trace)
runtime·printf("*** F[%d] = abs F[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeeb40bc0: // D[regd] :: D[regm] (CMPD)
runtime·fcmp64c(getd(regd), getd(regm), &cmp, &nan);
m->fflag = fstatus(nan, cmp);
if(trace)
runtime·printf("*** cmp D[%d]::D[%d] %x\n",
regd, regm, m->fflag);
break;
case 0xeeb40ac0: // F[regd] :: F[regm] (CMPF)
runtime·fcmp64c(f2d(m->freglo[regd]), f2d(m->freglo[regm]), &cmp, &nan);
m->fflag = fstatus(nan, cmp);
if(trace)
runtime·printf("*** cmp F[%d]::F[%d] %x\n",
regd, regm, m->fflag);
break;
case 0xeeb70ac0: // D[regd] = F[regm] (MOVFD)
putd(regd, f2d(m->freglo[regm]));
if(trace)
runtime·printf("*** f2d D[%d]=F[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb70bc0: // F[regd] = D[regm] (MOVDF)
m->freglo[regd] = d2f(getd(regm));
if(trace)
runtime·printf("*** d2f F[%d]=D[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeebd0ac0: // S[regd] = F[regm] (MOVFW)
runtime·f64tointc(f2d(m->freglo[regm]), &sval, &ok);
if(!ok || (int32)sval != sval)
sval = 0;
m->freglo[regd] = sval;
if(trace)
runtime·printf("*** fix S[%d]=F[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeebc0ac0: // S[regd] = F[regm] (MOVFW.U)
runtime·f64tointc(f2d(m->freglo[regm]), &sval, &ok);
if(!ok || (uint32)sval != sval)
sval = 0;
m->freglo[regd] = sval;
if(trace)
runtime·printf("*** fix unsigned S[%d]=F[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeebd0bc0: // S[regd] = D[regm] (MOVDW)
runtime·f64tointc(getd(regm), &sval, &ok);
if(!ok || (int32)sval != sval)
sval = 0;
m->freglo[regd] = sval;
if(trace)
runtime·printf("*** fix S[%d]=D[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeebc0bc0: // S[regd] = D[regm] (MOVDW.U)
runtime·f64tointc(getd(regm), &sval, &ok);
if(!ok || (uint32)sval != sval)
sval = 0;
m->freglo[regd] = sval;
if(trace)
runtime·printf("*** fix unsigned S[%d]=D[%d] %x\n",
regd, regm, m->freglo[regd]);
break;
case 0xeeb80ac0: // D[regd] = S[regm] (MOVWF)
cmp = m->freglo[regm];
if(cmp < 0) {
runtime·fintto64c(-cmp, &uval);
putf(regd, d2f(uval));
m->freglo[regd] ^= 0x80000000;
} else {
runtime·fintto64c(cmp, &uval);
putf(regd, d2f(uval));
}
if(trace)
runtime·printf("*** float D[%d]=S[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb80a40: // D[regd] = S[regm] (MOVWF.U)
runtime·fintto64c(m->freglo[regm], &uval);
putf(regd, d2f(uval));
if(trace)
runtime·printf("*** float unsigned D[%d]=S[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb80bc0: // D[regd] = S[regm] (MOVWD)
cmp = m->freglo[regm];
if(cmp < 0) {
runtime·fintto64c(-cmp, &uval);
putd(regd, uval);
m->freghi[regd] ^= 0x80000000;
} else {
runtime·fintto64c(cmp, &uval);
putd(regd, uval);
}
if(trace)
runtime·printf("*** float D[%d]=S[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
case 0xeeb80b40: // D[regd] = S[regm] (MOVWD.U)
runtime·fintto64c(m->freglo[regm], &uval);
putd(regd, uval);
if(trace)
runtime·printf("*** float unsigned D[%d]=S[%d] %x-%x\n",
regd, regm, m->freghi[regd], m->freglo[regd]);
break;
}
return 1;
done:
if((i&0xff000000) == 0xee000000 ||
(i&0xff000000) == 0xed000000) {
runtime·printf("stepflt %p %x\n", pc, i);
fabort();
}
return 0;
}
typedef struct Sfregs Sfregs;
// NOTE: These are all recorded as pointers because they are possibly live registers,
// and we don't know what they contain. Recording them as pointers should be
// safer than not.
struct Sfregs
{
uint32 *r0;
uint32 *r1;
uint32 *r2;
uint32 *r3;
uint32 *r4;
uint32 *r5;
uint32 *r6;
uint32 *r7;
uint32 *r8;
uint32 *r9;
uint32 *r10;
uint32 *r11;
uint32 *r12;
uint32 *r13;
uint32 cspr;
};
static void sfloat2(void);
void _sfloatpanic(void);
#pragma textflag NOSPLIT
uint32*
runtime·_sfloat2(uint32 *pc, Sfregs regs)
{
void (*fn)(void);
g->m->ptrarg[0] = pc;
g->m->ptrarg[1] = &regs;
fn = sfloat2;
runtime·onM(&fn);
pc = g->m->ptrarg[0];
g->m->ptrarg[0] = nil;
return pc;
}
static void
sfloat2(void)
{
uint32 *pc;
G *curg;
Sfregs *regs;
int32 skip;
bool first;
pc = g->m->ptrarg[0];
regs = g->m->ptrarg[1];
g->m->ptrarg[0] = nil;
g->m->ptrarg[1] = nil;
first = true;
while(skip = stepflt(pc, (uint32*)&regs->r0)) {
first = false;
if(skip == FAULT) {
// Encountered bad address in store/load.
// Record signal information and return to assembly
// trampoline that fakes the call.
enum { SIGSEGV = 11 };
curg = g->m->curg;
curg->sig = SIGSEGV;
curg->sigcode0 = 0;
curg->sigcode1 = 0;
curg->sigpc = (uint32)pc;
pc = (uint32*)_sfloatpanic;
break;
}
pc += skip;
}
if(first) {
runtime·printf("sfloat2 %p %x\n", pc, *pc);
fabort(); // not ok to fail first instruction
}
g->m->ptrarg[0] = pc;
}
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