llvm-project/llvm
Pawel Bylica 57c2f7c756 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

llvm-svn: 235370
2015-04-21 06:28:36 +00:00
..
autoconf Try to unbreak Clang build to export LLVM_ABI_BREAKING_CHECKS, fixup for r233310. 2015-04-01 11:46:15 +00:00
bindings DebugInfo: Delete subclasses of DIScope 2015-04-20 22:10:08 +00:00
cmake Add targets to cmake for specific target components. 2015-04-20 18:22:05 +00:00
docs docs: Update Kaleidoscope for recent DI changes 2015-04-18 00:01:35 +00:00
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
projects Reverse the order libc++ and libc++abi are added in CMake. 2015-03-04 01:16:43 +00:00
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
.arcconfig
.clang-format
.clang-tidy
.gitignore Ignore compile_commands.json only at the root of the tree. 2015-03-26 18:55:42 +00:00
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
CODE_OWNERS.TXT Add myself as the Constant Folder owner. 2015-04-20 23:19:10 +00:00
CREDITS.TXT
LICENSE.TXT Update for a new year. 2015-03-12 01:25:29 +00:00
LLVMBuild.txt
Makefile
Makefile.common
Makefile.config.in Try to unbreak Clang build to export LLVM_ABI_BREAKING_CHECKS, fixup for r233310. 2015-04-01 11:46:15 +00:00
Makefile.rules Add support for SunOS function/data sections and associated 2015-03-03 20:54:29 +00:00
README.txt Revert test commit at revision 233535. 2015-03-30 12:39:03 +00:00
configure Try to unbreak Clang build to export LLVM_ABI_BREAKING_CHECKS, fixup for r233310. 2015-04-01 11:46:15 +00:00
llvm.spec.in

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