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LLVM backend for 6502
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a80d668215
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Chris Lattner a80d668215 Implement rdar://6480391, extending of equality icmp's to avoid a truncation. 
I noticed this in the code compiled for a routine using std::map, which produced
this code:
	%25 = tail call i32 @memcmp(i8* %24, i8* %23, i32 6) nounwind readonly
	%.lobit.i = lshr i32 %25, 31		; <i32> [#uses=1]
	%tmp.i = trunc i32 %.lobit.i to i8		; <i8> [#uses=1]
	%toBool = icmp eq i8 %tmp.i, 0		; <i1> [#uses=1]
	br i1 %toBool, label %bb3, label %bb4
which compiled to:

	call	L_memcmp$stub
	shrl	$31, %eax
	testb	%al, %al
	jne	LBB1_11	## 

with this change, we compile it to:

	call	L_memcmp$stub
	testl	%eax, %eax
	js	LBB1_11

This triggers all the time in common code, with patters like this:

	%169 = and i32 %ply, 1		; <i32> [#uses=1]
	%170 = trunc i32 %169 to i8		; <i8> [#uses=1]
	%toBool = icmp ne i8 %170, 0		; <i1> [#uses=1]

 	%7 = lshr i32 %6, 24		; <i32> [#uses=1]
	%9 = trunc i32 %7 to i8		; <i8> [#uses=1]
	%10 = icmp ne i8 %9, 0		; <i1> [#uses=1]

etc



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61985 91177308-0d34-0410-b5e6-96231b3b80d8
2009-01-09 07:47:06 +00:00
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cmake CMake: replace `rm' with portable invocations of cmake. 2009-01-07 19:24:44 +00:00
docs Get rid of the tagging functions and use PointerIntPair. 2009-01-05 16:05:32 +00:00
examples
include add a helper method. 2009-01-09 05:27:40 +00:00
lib Implement rdar://6480391, extending of equality icmp's to avoid a truncation. 2009-01-09 07:47:06 +00:00
projects
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test Implement rdar://6480391, extending of equality icmp's to avoid a truncation. 2009-01-09 07:47:06 +00:00
tools CMake: replace `rm' with portable invocations of cmake. 2009-01-07 19:24:44 +00:00
unittests Some generic clean-ups. Also make the StringMapEntryInitializer specialization apply only to the tests that are actually testing it. 2009-01-08 09:31:36 +00:00
utils remove some exclusions that don't exist anymore. 2009-01-08 19:02:03 +00:00
website
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configure Regenerate. 2009-01-04 23:12:30 +00:00
CREDITS.TXT * Moved author attribution to CREDITS.TXT 2009-01-08 16:40:25 +00:00
LICENSE.TXT Renamed Google Test license file from COPYING to LICENSE.TXT to match LLVM 2009-01-05 17:42:15 +00:00
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Makefile.rules Removed trailing whitespace. 2009-01-08 02:11:55 +00:00
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