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[PATCH] Fix combine's make_extraction (PR rtl-optimization/78378)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 16 Nov 2016 22:07:23 +0100
- Subject: [PATCH] Fix combine's make_extraction (PR rtl-optimization/78378)
- Authentication-results: sourceware.org; auth=none
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
If inner is a MEM, make_extraction requires that pos is a multiple of bytes
and deals with offsetting it. Or otherwise requires that pos is a multiple
of BITS_PER_WORD and for REG inner it handles that too. But if inner
is something different, it calls just force_to_mode to the target mode,
which only really works if pos is 0.
Thus the following patch restricts it to that case.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2016-11-16 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/78378
* combine.c (make_extraction): Use force_to_mode for non-{REG,MEM}
inner only if pos is 0. Fix up formatting.
* gcc.c-torture/execute/pr78378.c: New test.
--- gcc/combine.c.jj 2016-11-16 18:51:58.000000000 +0100
+++ gcc/combine.c 2016-11-16 19:52:12.735674000 +0100
@@ -7382,6 +7382,7 @@ make_extraction (machine_mode mode, rtx
if (tmode != BLKmode
&& ((pos_rtx == 0 && (pos % BITS_PER_WORD) == 0
&& !MEM_P (inner)
+ && (pos == 0 || REG_P (inner))
&& (inner_mode == tmode
|| !REG_P (inner)
|| TRULY_NOOP_TRUNCATION_MODES_P (tmode, inner_mode)
@@ -7458,10 +7459,9 @@ make_extraction (machine_mode mode, rtx
}
else
new_rtx = force_to_mode (inner, tmode,
- len >= HOST_BITS_PER_WIDE_INT
- ? HOST_WIDE_INT_M1U
- : (HOST_WIDE_INT_1U << len) - 1,
- 0);
+ len >= HOST_BITS_PER_WIDE_INT
+ ? HOST_WIDE_INT_M1U
+ : (HOST_WIDE_INT_1U << len) - 1, 0);
/* If this extraction is going into the destination of a SET,
make a STRICT_LOW_PART unless we made a MEM. */
--- gcc/testsuite/gcc.c-torture/execute/pr78378.c.jj 2016-11-16 20:02:16.975248597 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr78378.c 2016-11-16 20:02:03.000000000 +0100
@@ -0,0 +1,18 @@
+/* PR rtl-optimization/78378 */
+
+unsigned long long __attribute__ ((noinline, noclone))
+foo (unsigned long long x)
+{
+ x <<= 41;
+ x /= 232;
+ return 1 + (unsigned short) x;
+}
+
+int
+main ()
+{
+ unsigned long long x = foo (1);
+ if (x != 0x2c24)
+ __builtin_abort();
+ return 0;
+}
Jakub