| Message ID | 20211026230943.1225890-47-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | tcg: optimize redundant sign extensions | expand |
On 10/27/21 01:09, Richard Henderson wrote: > Recognize the constant function for remainder. > > Suggested-by: Luis Pires <luis.pires@eldorado.org.br> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > tcg/optimize.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
From: Richard Henderson <richard.henderson@linaro.org> > static bool fold_remainder(OptContext *ctx, TCGOp *op) { > - return fold_const2(ctx, op); > + if (fold_const2(ctx, op) || > + fold_xx_to_i(ctx, op, 1)) { Should this be fold_xx_to_i(ctx, op, 0)? If arg[2] is 0, we would have different results than do_constant_folding(), but not sure we care, since the result is documented as undefined. -- Luis Pires Instituto de Pesquisas ELDORADO Aviso Legal - Disclaimer <https://www.eldorado.org.br/disclaimer.html>
On 10/27/21 1:42 PM, Luis Fernando Fujita Pires wrote: > From: Richard Henderson <richard.henderson@linaro.org> > >> static bool fold_remainder(OptContext *ctx, TCGOp *op) { >> - return fold_const2(ctx, op); >> + if (fold_const2(ctx, op) || >> + fold_xx_to_i(ctx, op, 1)) { > > Should this be fold_xx_to_i(ctx, op, 0)? Oops. I can only guess it's a cut-and-paste error. > If arg[2] is 0, we would have different results than do_constant_folding(), but not sure we care, since the result is documented as undefined. At first I thought you meant a known 0, but you mean some unknown value which happens to be 0 at runtime. Yes, we do get a different value, but yes, we don't care because undefined. r~
diff --git a/tcg/optimize.c b/tcg/optimize.c index 92684d4b1d..6c6c523a85 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -1623,7 +1623,11 @@ static bool fold_qemu_st(OptContext *ctx, TCGOp *op) static bool fold_remainder(OptContext *ctx, TCGOp *op) { - return fold_const2(ctx, op); + if (fold_const2(ctx, op) || + fold_xx_to_i(ctx, op, 1)) { + return true; + } + return false; } static bool fold_setcond(OptContext *ctx, TCGOp *op)
Recognize the constant function for remainder. Suggested-by: Luis Pires <luis.pires@eldorado.org.br> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- tcg/optimize.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)