Combine expands things like
(zero_extend:DI (lshiftrt:SI (reg:SI) (reg:SI)))
to
(and:DI (subreg:DI (lshiftrt:SI (reg:SI) (reg:SI)) 0)
(const_int 0xffffffff))
to do simplifications on, and then make_compound_operation is supposed
to transform it back to the simpler form (with the zero_extend).
But it doesn't; it tries to make a zero_extract and then gives up.
This fixes it. Bootstrapped and regression tested on powerpc64-linux
(-m32,-m32/-mpowerpc64,-m64,-m64/-mlra); no regressions. Committing.
Segher
2015-07-02 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/66706
* combine.c (make_compound_operation): If an AND of SUBREG of
LSHIFTRT does not simplify, see if just the AND of SUBREG does.
---
gcc/combine.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/gcc/combine.c b/gcc/combine.c
index 8eaae7c..b97aa10 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -7893,6 +7893,15 @@ make_compound_operation (rtx x, enum rtx_code in_code)
new_rtx = make_extraction (GET_MODE (SUBREG_REG (XEXP (x, 0))),
new_rtx, 0,
XEXP (SUBREG_REG (XEXP (x, 0)), 1), i, 1,
0, in_code == COMPARE);
+
+ /* If that didn't give anything, see if the AND simplifies on
+ its own. */
+ if (!new_rtx && i >= 0)
+ {
+ new_rtx = make_compound_operation (XEXP (x, 0), next_code);
+ new_rtx = make_extraction (mode, new_rtx, 0, NULL_RTX, i, 1,
+ 0, in_code == COMPARE);
+ }
}
/* Same as previous, but for (xor/ior (lshiftrt...) (lshiftrt...)). */
else if ((GET_CODE (XEXP (x, 0)) == XOR
--
1.8.1.4
