Chris Lattner 895c4ab564 Fold (x << c1)>> c2 into a single shift if the bits shifted out aren't used.
This compiles:
int baz(long long a) { return (short)(((int)(a >>24)) >> 9); }

into:
_baz:
        srwi r2, r3, 1
        extsh r3, r2
        blr

on PPC, instead of:
_baz:
        slwi r2, r3, 8
        srwi r2, r2, 9
        extsh r3, r2
        blr

GCC produces:
_baz:
        srwi r10,r4,24
        insrwi r10,r3,24,0
        srawi r9,r3,24
        srawi r3,r10,9
        extsh r3,r3
        blr

This implements CodeGen/PowerPC/shl_elim.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36221 91177308-0d34-0410-b5e6-96231b3b80d8
2007-04-17 21:14:16 +00:00
2007-04-17 21:12:26 +00:00
2007-04-16 03:05:01 +00:00
2007-04-16 06:54:34 +00:00
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2007-01-29 18:45:08 +00:00
2006-10-18 19:23:56 +00:00
2007-03-21 21:45:25 +00:00
2007-02-25 02:28:21 +00:00
2007-03-29 19:05:44 +00:00

Low Level Virtual Machine (LLVM)
================================

This directory and its subdirectories contain source code for the Low Level 
Virtual Machine, a toolkit for the construction of highly optimized compilers,
optimizers, and runtime environments. 

LLVM is open source software. You may freely distribute it under the terms of
the license agreement found in LICENSE.txt.

Please see the HTML documentation provided in docs/index.html for further
assistance with LLVM.
Description
LLVM backend for 6502
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