To...

To: gcc-patches@gcc.gnu.org
Subject: Add an extra pow rule to match.pd
From: Richard Sandiford <richard.sandiford@arm.com>
Gcc: private.sent
--text follows this line--
Simplify pow(|x|,y) and pow(-x,y) to pow(x,y) if y is an even integer.
At the moment this duplicates a case in fold_builtin_pow, but an
upcoming patch will move all the fold_builtin_pow rules to match.pd.
I'm doing this one early to fix a regression in builtin-10.c for
soft-float ARM.

gcc/
	* real.h (real_isinteger): Declare.
	* real.c (real_isinteger): New function.
	* match.pd: Simplify pow(|x|,y) and pow(-x,y) to pow(x,y)
	if y is an even integer.

From-SVN: r228750

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/real.c b/gcc/real.c
index f633ffd2e88..85ac83d3fdc 100644
--- a/gcc/real.c
+++ b/gcc/real.c
@@ -4997,6 +4997,24 @@ real_isinteger (const REAL_VALUE_TYPE *c, machine_mode mode)
   return real_identical (c, &cint);
 }
 
+/* Check whether C is an integer that fits in a HOST_WIDE_INT,
+   storing it in *INT_OUT if so.  */
+
+bool
+real_isinteger (const REAL_VALUE_TYPE *c, HOST_WIDE_INT *int_out)
+{
+  REAL_VALUE_TYPE cint;
+
+  HOST_WIDE_INT n = real_to_integer (c);
+  real_from_integer (&cint, VOIDmode, n, SIGNED);
+  if (real_identical (c, &cint))
+    {
+      *int_out = n;
+      return true;
+    }
+  return false;
+}
+
 /* Write into BUF the maximum representable finite floating-point
    number, (1 - b**-p) * b**emax for a given FP format FMT as a hex
    float string.  LEN is the size of BUF, and the buffer must be large