The comment for the added case to simplify_truncation reads
/* Turn (truncate:M1 (*_extract:M2 (reg:M2) (len) (pos))) into
(*_extract:M1 (truncate:M1 (reg:M2)) (len) (pos')) if possible without
changing len. */
but I forget to check the two modes M2 are actually the same. Tested on
powerpc64-linux, committing to trunk as obvious.
Segher
2016-11-30 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/78583
* simplify-rtx.c (simplify_truncation): Add check missing from the
previous commit.
---
gcc/simplify-rtx.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index f922aaf..ead2f5a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -752,6 +752,7 @@ simplify_truncation (machine_mode mode, rtx op,
changing len. */
if ((GET_CODE (op) == ZERO_EXTRACT || GET_CODE (op) == SIGN_EXTRACT)
&& REG_P (XEXP (op, 0))
+ && GET_MODE (XEXP (op, 0)) == mode
&& CONST_INT_P (XEXP (op, 1))
&& CONST_INT_P (XEXP (op, 2)))
{
--
1.9.3
