simplify-rtx: Fix compare of comparisons (PR60818)

The function simplify_binary_operation_1 has code that does
/* Convert (compare (gt (flags) 0) (lt (flags) 0)) to (flags).  */
but this transformation is only valid if "flags" has the same machine
mode as the outer compare.  This fixes it.

	PR rtl-optimization/60818
	* simplify-rtx.c (simplify_binary_operation_1): Do not replace
	a compare of comparisons with the thing compared if this results
	in a different machine mode.

gcc/testsuite/
	PR rtl-optimization/60818
	* gcc.c-torture/compile/pr60818.c: New testcase.

From-SVN: r246666

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a92c3a5b5e074098ce0458b38ef69bb7b40fc4e7..4d113af985d293e5282966defc40e166b328290e 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2017-04-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+       PR rtl-optimization/60818
+       * simplify-rtx.c (simplify_binary_operation_1): Do not replace
+       a compare of comparisons with the thing compared if this results
+       in a different machine mode.
+
 2017-04-03  Jonathan Wakely  <jwakely@redhat.com>
 
        * alias.c (base_alias_check): Fix typo in comment.

diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 640ccb7cb95933a6991bf1599099f7aed455daec..cff7e4d3e3f15a9ecda18e8396c82d5b8b76710e 100644 (file)
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -2306,10 +2306,10 @@ simplify_binary_operation_1 (enum rtx_code code, machine_mode mode,
              return xop00;
 
            if (REG_P (xop00) && REG_P (xop10)
-               && GET_MODE (xop00) == GET_MODE (xop10)
                && REGNO (xop00) == REGNO (xop10)
-               && GET_MODE_CLASS (GET_MODE (xop00)) == MODE_CC
-               && GET_MODE_CLASS (GET_MODE (xop10)) == MODE_CC)
+               && GET_MODE (xop00) == mode
+               && GET_MODE (xop10) == mode
+               && GET_MODE_CLASS (mode) == MODE_CC)
              return xop00;
        }
       break;

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4a05eba88b9950a5b15dc8a931668a9585b5b8ab..9ac0c0b8dc985e4eb6126d40b6e18acb9b2c2d50 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-04-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+       PR rtl-optimization/60818
+       * gcc.c-torture/compile/pr60818.c: New testcase.
+
 2017-04-03  Jonathan Wakely  <jwakely@redhat.com>
 
        * g++.old-deja/g++.benjamin/scope02.C: Fix typo in comment.

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr60818.c b/gcc/testsuite/gcc.c-torture/compile/pr60818.c
new file mode 100644 (file)
index 0000000..b6171bb
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr60818.c
@@ -0,0 +1,5 @@
+int
+lx (int oi, int mb)
+{
+  return (oi < mb) < (mb < oi);
+}