[PATCH v2, i386]: Fix PR78738, unrecognized insn with -ffast-math

[Uros Bizjak]

Hello!

Attached patch fixes PR78738 in a different way. The patch enables
X87_ENABLE_ARITH and X87_ENABLE_FLOAT also for
flag_unsafe_math_optimizations.

2016-12-12  Uros Bizjak  <ubiz...@gmail.com>

    PR target/78738
    * config/i386/i386.h (X87_ENABLE_ARITH): Also enable for
    flag_unsafe_math_optimizations.
    (X87_ENABLE_FLOAT): Ditto.

testsuite/ChangeLog:

2016-12-12  Uros Bizjak  <ubiz...@gmail.com>

    PR target/78738
    * gcc.target/i386/pr78738.c: New test.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline SVN.

Uros.

Index: config/i386/i386.h
===================================================================
--- config/i386/i386.h  (revision 243558)
+++ config/i386/i386.h  (working copy)
@@ -693,13 +693,16 @@
 /* Whether to allow x87 floating-point arithmetic on MODE (one of
    SFmode, DFmode and XFmode) in the current excess precision
    configuration.  */
-#define X87_ENABLE_ARITH(MODE) \
-  (flag_excess_precision == EXCESS_PRECISION_FAST || (MODE) == XFmode)
+#define X87_ENABLE_ARITH(MODE)                         \
+  (flag_unsafe_math_optimizations                      \
+   || flag_excess_precision == EXCESS_PRECISION_FAST   \
+   || (MODE) == XFmode)
 
 /* Likewise, whether to allow direct conversions from integer mode
    IMODE (HImode, SImode or DImode) to MODE.  */
 #define X87_ENABLE_FLOAT(MODE, IMODE)                  \
-  (flag_excess_precision == EXCESS_PRECISION_FAST      \
+  (flag_unsafe_math_optimizations                      \
+   || flag_excess_precision == EXCESS_PRECISION_FAST   \
    || (MODE) == XFmode                                 \
    || ((MODE) == DFmode && (IMODE) == SImode)          \
    || (IMODE) == HImode)
Index: testsuite/gcc.target/i386/pr78738.c
===================================================================
--- testsuite/gcc.target/i386/pr78738.c (nonexistent)
+++ testsuite/gcc.target/i386/pr78738.c (working copy)
@@ -0,0 +1,10 @@
+/* PR middle-end/78738 */
+/* { dg-do compile } */
+/* { dg-options "-O -std=c99 -ffast-math -mfpmath=387" } */
+
+double round (double);
+
+int foo (double a)
+{
+  return round (a);
+}