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FPU: saturate float-to-int in the interpreters
The C cast is undefined past the int32 range, and x86 makes it INT_MIN, so round/trunc/ceil/floor/cvt.w.s of anything from 2^31 up gave 0x80000000 on x86 hosts while the PSP saturates to 0x7fffffff (cpu/fpu/roundmode). Route all of them through SaturatedFloatToInt, which also covers NaN and inf, and drop the special cases that did. Co-Authored-By: Claude Fable 5.1 <[email protected]>
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Henrik RydgårdandClaude Fable 5.1 committed
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@@ -127,6 +127,19 @@ inline int is_even(float d) {
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return 2.0f * int_part == d;
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}
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// Float to int the way the PSP's FPU does it: at or past the int32 range the result is the nearest
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// limit, and a NaN gives INT_MAX whatever its sign (cpu/fpu/roundmode). The plain cast is undefined
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// there, and x86 makes it INT_MIN. Takes a value that's already been rounded.
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inline int32_t SaturatedFloatToInt(double d) {
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if (d >= 2147483648.0)
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return 0x7FFFFFFF;
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if (d <= -2147483648.0)
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return (int32_t)0x80000000;
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if (d != d)
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return 0x7FFFFFFF;
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return (int32_t)d;
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}
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// Rounds *.5 to closest even number
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inline double round_ieee_754(double d) {
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float i = (float)floor(d);
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@@ -928,58 +928,17 @@ u32 IRInterpret(MIPSState *mips, const IRInst *inst) {
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mips->r[inst->dest] = mips->vfpuCtrl[inst->src1];
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break;
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case IROp::FRound:
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{
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float value = mips->f[inst->src1];
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if (my_isnanorinf(value)) {
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mips->fi[inst->dest] = my_isinf(value) && value < 0.0f ? -2147483648LL : 2147483647LL;
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mips->fs[inst->dest] = SaturatedFloatToInt(round_ieee_754(mips->f[inst->src1]));
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break;
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} else {
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mips->fs[inst->dest] = (int)round_ieee_754(value);
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}
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break;
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}
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case IROp::FTrunc:
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{
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float value = mips->f[inst->src1];
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if (my_isnanorinf(value)) {
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mips->fi[inst->dest] = my_isinf(value) && value < 0.0f ? -2147483648LL : 2147483647LL;
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mips->fs[inst->dest] = SaturatedFloatToInt(truncf(mips->f[inst->src1]));
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break;
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} else {
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if (value >= 0.0f) {
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mips->fs[inst->dest] = (int)floorf(value);
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// Overflow, but it was positive.
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if (mips->fs[inst->dest] == -2147483648LL) {
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mips->fs[inst->dest] = 2147483647LL;
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}
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} else {
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// Overflow happens to be the right value anyway.
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mips->fs[inst->dest] = (int)ceilf(value);
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}
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break;
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}
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}
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case IROp::FCeil:
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{
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float value = mips->f[inst->src1];
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if (my_isnanorinf(value)) {
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mips->fi[inst->dest] = my_isinf(value) && value < 0.0f ? -2147483648LL : 2147483647LL;
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mips->fs[inst->dest] = SaturatedFloatToInt(ceilf(mips->f[inst->src1]));
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break;
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} else {
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mips->fs[inst->dest] = (int)ceilf(value);
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}
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break;
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}
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case IROp::FFloor:
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{
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float value = mips->f[inst->src1];
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if (my_isnanorinf(value)) {
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mips->fi[inst->dest] = my_isinf(value) && value < 0.0f ? -2147483648LL : 2147483647LL;
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mips->fs[inst->dest] = SaturatedFloatToInt(floorf(mips->f[inst->src1]));
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break;
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} else {
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mips->fs[inst->dest] = (int)floorf(value);
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}
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break;
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}
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case IROp::FCmp:
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switch (inst->dest) {
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case IRFpCompareMode::False:
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@@ -1019,16 +978,12 @@ u32 IRInterpret(MIPSState *mips, const IRInst *inst) {
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case IROp::FCvtWS:
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{
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float src = mips->f[inst->src1];
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if (my_isnanorinf(src)) {
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mips->fs[inst->dest] = my_isinf(src) && src < 0.0f ? -2147483648LL : 2147483647LL;
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break;
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}
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// TODO: Inline assembly to use here would be better.
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switch (IRRoundMode(mips->fcr31 & 3)) {
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case IRRoundMode::RINT_0: mips->fs[inst->dest] = (int)round_ieee_754(src); break;
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case IRRoundMode::CAST_1: mips->fs[inst->dest] = (int)src; break;
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case IRRoundMode::CEIL_2: mips->fs[inst->dest] = (int)ceilf(src); break;
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case IRRoundMode::FLOOR_3: mips->fs[inst->dest] = (int)floorf(src); break;
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case IRRoundMode::RINT_0: mips->fs[inst->dest] = SaturatedFloatToInt(round_ieee_754(src)); break;
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case IRRoundMode::CAST_1: mips->fs[inst->dest] = SaturatedFloatToInt(truncf(src)); break;
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case IRRoundMode::CEIL_2: mips->fs[inst->dest] = SaturatedFloatToInt(ceilf(src)); break;
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case IRRoundMode::FLOOR_3: mips->fs[inst->dest] = SaturatedFloatToInt(floorf(src)); break;
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}
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break; //cvt.w.s
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}
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@@ -1130,46 +1130,25 @@ namespace MIPSInt {
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case 13:
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case 14:
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case 15:
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if (my_isnanorinf(F(fs)))
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{
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FsI(fd) = my_isinf(F(fs)) && F(fs) < 0.0f ? -2147483648LL : 2147483647LL;
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break;
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}
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switch (op & 0x3f)
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{
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// round.w.s is round-half-to-even, not half-away-from-zero - and its mode is fixed,
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// so unlike cvt.w.s below it must not follow fcr31. round_ieee_754 is both.
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case 12: FsI(fd) = (int)round_ieee_754(F(fs)); break; //round.w.s
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case 13: //trunc.w.s
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if (F(fs) >= 0.0f) {
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FsI(fd) = (int)floorf(F(fs));
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// Overflow, but it was positive.
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if (FsI(fd) == -2147483648LL) {
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FsI(fd) = 2147483647LL;
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}
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} else {
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// Overflow happens to be the right value anyway.
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FsI(fd) = (int)ceilf(F(fs));
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}
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break;
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case 14: FsI(fd) = (int)ceilf (F(fs)); break; //ceil.w.s
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case 15: FsI(fd) = (int)floorf(F(fs)); break; //floor.w.s
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case 12: FsI(fd) = SaturatedFloatToInt(round_ieee_754(F(fs))); break; //round.w.s
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case 13: FsI(fd) = SaturatedFloatToInt(truncf(F(fs))); break; //trunc.w.s
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case 14: FsI(fd) = SaturatedFloatToInt(ceilf(F(fs))); break; //ceil.w.s
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case 15: FsI(fd) = SaturatedFloatToInt(floorf(F(fs))); break; //floor.w.s
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}
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break;
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case 32: F(fd) = (float)FsI(fs); break; //cvt.s.w
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case 36:
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if (my_isnanorinf(F(fs)))
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{
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FsI(fd) = my_isinf(F(fs)) && F(fs) < 0.0f ? -2147483648LL : 2147483647LL;
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break;
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}
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switch (mips->fcr31 & 3)
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{
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case 0: FsI(fd) = (int)round_ieee_754(F(fs)); break; // RINT_0
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case 1: FsI(fd) = (int)F(fs); break; // CAST_1
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case 2: FsI(fd) = (int)ceilf(F(fs)); break; // CEIL_2
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case 3: FsI(fd) = (int)floorf(F(fs)); break; // FLOOR_3
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case 0: FsI(fd) = SaturatedFloatToInt(round_ieee_754(F(fs))); break; // RINT_0
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case 1: FsI(fd) = SaturatedFloatToInt(truncf(F(fs))); break; // CAST_1
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case 2: FsI(fd) = SaturatedFloatToInt(ceilf(F(fs))); break; // CEIL_2
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case 3: FsI(fd) = SaturatedFloatToInt(floorf(F(fs))); break; // FLOOR_3
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}
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break; //cvt.w.s
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default:
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