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-rw-r--r--gcc/combine.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/gcc/combine.c b/gcc/combine.c
index 473ffc4..e74ff4c 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -11289,8 +11289,13 @@ change_zero_ext (rtx pat)
else
continue;
- wide_int mask = wi::mask (size, false, GET_MODE_PRECISION (mode));
- x = gen_rtx_AND (mode, x, immed_wide_int_const (mask, mode));
+ if (!(GET_CODE (x) == LSHIFTRT
+ && CONST_INT_P (XEXP (x, 1))
+ && size + INTVAL (XEXP (x, 1)) == GET_MODE_PRECISION (mode)))
+ {
+ wide_int mask = wi::mask (size, false, GET_MODE_PRECISION (mode));
+ x = gen_rtx_AND (mode, x, immed_wide_int_const (mask, mode));
+ }
SUBST (**iter, x);
changed = true;