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.
Bootstrapped and tested on powerpc64-linux {-m32,-m64} (and tested the
new testcase with {-m32,-m64}{,-misel}). Is this okay for trunk?
Segher
2017-03-31 Segher Boessenkool <seg...@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.
gcc/testsuite/
PR rtl-optimization/60818
* gcc.c-torture/compile/pr60818.c: New testcase.
---
gcc/simplify-rtx.c | 6 +++---
gcc/testsuite/gcc.c-torture/compile/pr60818.c | 5 +++++
2 files changed, 8 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr60818.c
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 3022779..10c2800 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -2367,10 +2367,10 @@
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/gcc.c-torture/compile/pr60818.c
b/gcc/testsuite/gcc.c-torture/compile/pr60818.c
new file mode 100644
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);
+}
--
1.9.3
