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authorRichard Biener <rguenther@suse.de>2021-10-27 14:27:40 +0200
committerRichard Biener <rguenther@suse.de>2021-10-28 11:28:42 +0200
commita84b9d5373c7e67fd0ab2a412c22162cdf969c91 (patch)
treed3211aa3a240ba0ab3043df237ed2ac37a35f5a9 /gcc
parenteed248bb8cc3091e8a9b2f73138c691396752438 (diff)
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middle-end/57245 - honor -frounding-math in real truncation
The following honors -frounding-math when converting a FP constant to another FP type. 2021-10-27 Richard Biener <rguenther@suse.de> PR middle-end/57245 * fold-const.c (fold_convert_const_real_from_real): Honor -frounding-math if the conversion is not exact. * simplify-rtx.c (simplify_const_unary_operation): Do not simplify FLOAT_TRUNCATE with sign dependent rounding. * gcc.dg/torture/fp-double-convert-float-1.c: New testcase.
Diffstat (limited to 'gcc')
-rw-r--r--gcc/fold-const.c6
-rw-r--r--gcc/simplify-rtx.c5
-rw-r--r--gcc/testsuite/gcc.dg/torture/fp-double-convert-float-1.c41
3 files changed, 52 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index ff23f12..18950ae 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -2139,6 +2139,12 @@ fold_convert_const_real_from_real (tree type, const_tree arg1)
&& REAL_VALUE_ISSIGNALING_NAN (TREE_REAL_CST (arg1)))
return NULL_TREE;
+ /* With flag_rounding_math we should respect the current rounding mode
+ unless the conversion is exact. */
+ if (HONOR_SIGN_DEPENDENT_ROUNDING (arg1)
+ && !exact_real_truncate (TYPE_MODE (type), &TREE_REAL_CST (arg1)))
+ return NULL_TREE;
+
real_convert (&value, TYPE_MODE (type), &TREE_REAL_CST (arg1));
t = build_real (type, value);
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index bbbd6b7..f38b6d7 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -2068,6 +2068,11 @@ simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
and the operand is a signaling NaN. */
if (HONOR_SNANS (mode) && REAL_VALUE_ISSIGNALING_NAN (d))
return NULL_RTX;
+ /* Or if flag_rounding_math is on and the truncation is not
+ exact. */
+ if (HONOR_SIGN_DEPENDENT_ROUNDING (mode)
+ && !exact_real_truncate (mode, &d))
+ return NULL_RTX;
d = real_value_truncate (mode, d);
break;
case FLOAT_EXTEND:
diff --git a/gcc/testsuite/gcc.dg/torture/fp-double-convert-float-1.c b/gcc/testsuite/gcc.dg/torture/fp-double-convert-float-1.c
new file mode 100644
index 0000000..ec23274
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/fp-double-convert-float-1.c
@@ -0,0 +1,41 @@
+/* PR57245 */
+/* { dg-do run } */
+/* { dg-require-effective-target fenv } */
+/* { dg-additional-options "-frounding-math" } */
+
+#include <fenv.h>
+#include <stdlib.h>
+
+int
+main ()
+{
+#if __DBL_MANT_DIG__ == 53 && __FLT_MANT_DIG__ == 24
+#ifdef FE_UPWARD
+ fesetround (FE_UPWARD);
+ float f = 1.3;
+ if (f != 0x1.4ccccep+0f)
+ __builtin_abort ();
+#endif
+#ifdef FE_TONEAREST
+ fesetround (FE_TONEAREST);
+ /* Use different actual values so the bogus CSE we perform does not
+ break things. */
+ f = 1.33;
+ if (f != 0x1.547ae2p+0f)
+ abort ();
+#endif
+#ifdef FE_DOWNWARD
+ fesetround (FE_DOWNWARD);
+ f = 1.333;
+ if (f != 0x1.553f7cp+0f)
+ abort ();
+#endif
+#ifdef FE_TOWARDZERO
+ fesetround (FE_TOWARDZERO);
+ f = 1.3333;
+ if (f != 0x1.555326p+0f)
+ abort ();
+#endif
+#endif
+ return 0;
+}