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Pawel Bylica 775c174b7b Fix generic shift expansion when shift amount is 0
Summary:
This fixes http://llvm.org/bugs/show_bug.cgi?id=16439. 

This is one possible way to approach this. The other would be to split InL>>(nbits-Amt) into (InL>>(nbits-1-Amt))>>1, which is also valid since since we only need to care about Amt up nbits-1. It's hard to tell which one is better since the shift might be expensive if this stage of expansion is not yet a legal machine integer, whereas comparisons with zero are relatively cheap at all sizes, but more expensive than a shift if the shift is on a legal machine type. 

Patch by Keno Fischer!

Test Plan: regression test from http://reviews.llvm.org/D7752

Reviewers: chfast, resistor

Reviewed By: chfast, resistor

Subscribers: sanjoy, resistor, chfast, llvm-commits

Differential Revision: http://reviews.llvm.org/D4978



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235370 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-21 06:28:36 +00:00
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examples DebugInfo: Fix Kaleidoscope Ch. 8 after r235327 2015-04-20 21:29:44 +00:00
include DebugInfo: Delete subclasses of DIScope 2015-04-20 22:10:08 +00:00
lib Fix generic shift expansion when shift amount is 0 2015-04-21 06:28:36 +00:00
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test Fix generic shift expansion when shift amount is 0 2015-04-21 06:28:36 +00:00
tools bugpoint Enhancement. 2015-04-20 23:42:22 +00:00
unittests DebugInfo: Delete subclasses of DIScope 2015-04-20 22:10:08 +00:00
utils Enhanced vim support. 2015-04-21 01:35:42 +00:00
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CMakeLists.txt [CMake] Updates to llvm-shlib to support overriding exports list and added an option to export all symbols. 2015-04-13 21:29:46 +00:00
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