From: Richard Biener Date: Thu, 28 Oct 2021 09:38:32 +0000 (+0200) Subject: middle-end/84407 - honor -frounding-math for int to float conversion X-Git-Tag: basepoints/gcc-13~3546 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=81342e95827f77c0917dd7a9fd54ac9729439c8e;p=thirdparty%2Fgcc.git middle-end/84407 - honor -frounding-math for int to float conversion This makes us honor -frounding-math for integer to float conversions and avoid constant folding when such conversion is not exact. 2021-10-28 Richard Biener PR middle-end/84407 * fold-const.c (fold_convert_const): Avoid int to float constant folding with -frounding-math and inexact result. * simplify-rtx.c (simplify_const_unary_operation): Likewise for both float and unsigned_float. * gcc.dg/torture/fp-uint64-convert-double-1.c: New testcase. * gcc.dg/torture/fp-uint64-convert-double-2.c: Likewise. --- diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 18950aeb760d..c7daf8711256 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -2290,7 +2290,20 @@ fold_convert_const (enum tree_code code, tree type, tree arg1) else if (TREE_CODE (type) == REAL_TYPE) { if (TREE_CODE (arg1) == INTEGER_CST) - return build_real_from_int_cst (type, arg1); + { + tree res = build_real_from_int_cst (type, arg1); + /* Avoid the folding if flag_rounding_math is on and the + conversion is not exact. */ + if (HONOR_SIGN_DEPENDENT_ROUNDING (type)) + { + bool fail = false; + wide_int w = real_to_integer (&TREE_REAL_CST (res), &fail, + TYPE_PRECISION (TREE_TYPE (arg1))); + if (fail || wi::ne_p (w, wi::to_wide (arg1))) + return NULL_TREE; + } + return res; + } else if (TREE_CODE (arg1) == REAL_CST) return fold_convert_const_real_from_real (type, arg1); else if (TREE_CODE (arg1) == FIXED_CST) diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c index f38b6d7d31c7..a060f1bbce01 100644 --- a/gcc/simplify-rtx.c +++ b/gcc/simplify-rtx.c @@ -1917,6 +1917,19 @@ simplify_const_unary_operation (enum rtx_code code, machine_mode mode, return 0; d = real_value_truncate (mode, d); + + /* Avoid the folding if flag_rounding_math is on and the + conversion is not exact. */ + if (HONOR_SIGN_DEPENDENT_ROUNDING (mode)) + { + bool fail = false; + wide_int w = real_to_integer (&d, &fail, + GET_MODE_PRECISION + (as_a (op_mode))); + if (fail || wi::ne_p (w, wide_int (rtx_mode_t (op, op_mode)))) + return 0; + } + return const_double_from_real_value (d, mode); } else if (code == UNSIGNED_FLOAT && CONST_SCALAR_INT_P (op)) @@ -1941,6 +1954,19 @@ simplify_const_unary_operation (enum rtx_code code, machine_mode mode, return 0; d = real_value_truncate (mode, d); + + /* Avoid the folding if flag_rounding_math is on and the + conversion is not exact. */ + if (HONOR_SIGN_DEPENDENT_ROUNDING (mode)) + { + bool fail = false; + wide_int w = real_to_integer (&d, &fail, + GET_MODE_PRECISION + (as_a (op_mode))); + if (fail || wi::ne_p (w, wide_int (rtx_mode_t (op, op_mode)))) + return 0; + } + return const_double_from_real_value (d, mode); } diff --git a/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-1.c b/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-1.c new file mode 100644 index 000000000000..b40a16a22573 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-1.c @@ -0,0 +1,74 @@ +/* PR84407 */ +/* { dg-do run } */ +/* { dg-require-effective-target fenv } */ +/* { dg-additional-options "-frounding-math" } */ + +#include +#include + +void __attribute__((noipa)) +fooa () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_TONEAREST + fesetround(FE_TONEAREST); + __UINT64_TYPE__ x = 0x7fffffffffffffff; + double f = x; + if (f != 0x1p+63) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +foob () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_DOWNWARD + fesetround(FE_DOWNWARD); + __UINT64_TYPE__ x = 0x7fffffffffffffff; + double f = x; + if (f != 0x1.fffffffffffffp+62) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +fooc () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_UPWARD + fesetround(FE_UPWARD); + __UINT64_TYPE__ x = 0x7fffffffffffffff; + double f = x; + if (f != 0x1p+63) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +food () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_TOWARDZERO + fesetround(FE_TOWARDZERO); + __UINT64_TYPE__ x = 0x7fffffffffffffff; + double f = x; + if (f != 0x1.fffffffffffffp+62) + abort (); +#endif +#endif +} + + +int +main () +{ + fooa (); + foob (); + fooc (); + food (); + return 0; +} diff --git a/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-2.c b/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-2.c new file mode 100644 index 000000000000..952f96b33c92 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/fp-uint64-convert-double-2.c @@ -0,0 +1,75 @@ +/* PR84407 */ +/* { dg-do run } */ +/* { dg-require-effective-target fenv } */ +/* { dg-additional-options "-frounding-math" } */ + +#include +#include + +void __attribute__((noipa)) +fooa () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_TONEAREST + fesetround(FE_TONEAREST); + /* Large enough constant to trigger unsigned_float. */ + __UINT64_TYPE__ x = 0x8000000000000001; + double f = x; + if (f != 0x1p+63) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +foob () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_DOWNWARD + fesetround(FE_DOWNWARD); + __UINT64_TYPE__ x = 0x8000000000000001; + double f = x; + if (f != 0x1p+63) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +fooc () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_UPWARD + fesetround(FE_UPWARD); + __UINT64_TYPE__ x = 0x8000000000000001; + double f = x; + if (f != 0x1.0000000000001p+63) + abort (); +#endif +#endif +} + +void __attribute__((noipa)) +food () +{ +#if __DBL_MANT_DIG__ == 53 +#ifdef FE_TOWARDZERO + fesetround(FE_TOWARDZERO); + __UINT64_TYPE__ x = 0x8000000000000001; + double f = x; + if (f != 0x1p+63) + abort (); +#endif +#endif +} + + +int +main () +{ + fooa (); + foob (); + fooc (); + food (); + return 0; +}