diff options
| author | Richard Henderson <rth@cygnus.com> | 1998-03-25 16:20:08 -0800 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 1998-03-25 16:20:08 -0800 |
| commit | 6f28d3e98257593850baca079e60a59eae47bc9f (patch) | |
| tree | fa5c337155be729a7812e5f418eaaf7d3d5d0442 /gcc/combine.c | |
| parent | 7eea64437a974d93e6a99163ecb3d1b97d1c7e0d (diff) | |
| download | gcc-6f28d3e98257593850baca079e60a59eae47bc9f.zip gcc-6f28d3e98257593850baca079e60a59eae47bc9f.tar.gz gcc-6f28d3e98257593850baca079e60a59eae47bc9f.tar.bz2 | |
* combine.c (make_compound_operation): Simplify (subreg (*_extend) 0).
From-SVN: r18836
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 8cb32dc..4bef563 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -6038,6 +6038,23 @@ make_compound_operation (x, in_code) return newer; } + + /* If this is a paradoxical subreg, and the new code is a sign or + zero extension, omit the subreg and widen the extension. If it + is a regular subreg, we can still get rid of the subreg by not + widening so much, or in fact removing the extension entirely. */ + if ((GET_CODE (tem) == SIGN_EXTEND + || GET_CODE (tem) == ZERO_EXTEND) + && subreg_lowpart_p (x)) + { + if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (tem)) + || (GET_MODE_SIZE (mode) > + GET_MODE_SIZE (GET_MODE (XEXP (tem, 0))))) + tem = gen_rtx_combine (GET_CODE (tem), mode, XEXP (tem, 0)); + else + tem = gen_lowpart_for_combine (mode, XEXP (tem, 0)); + return tem; + } break; default: |