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Author SHA1 Message Date
Eric Christopher cee313d288 Revert "Temporarily Revert "Add basic loop fusion pass."" 
The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552
 2019-04-17 04:52:47 +00:00
Eric Christopher a863435128 Temporarily Revert "Add basic loop fusion pass." 
As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546
 2019-04-17 02:12:23 +00:00
Eli Friedman d4e7a0d83c [SimplifyLibCalls] Fix memchr expansion for constant strings. 
The C standard says "The memchr function locates the first
occurrence of c (converted to an unsigned char)[...]".  The expansion
was missing the conversion to unsigned char.

Fixes https://bugs.llvm.org/show_bug.cgi?id=39041 .

Differential Revision: https://reviews.llvm.org/D55947

llvm-svn: 350775
 2019-01-09 23:39:26 +00:00
Matthias Braun 50ec0b5dce SimplifyLibCalls: Optimize wcslen 
Refactor the strlen optimization code to work for both strlen and wcslen.

This especially helps with programs in the wild where people pass
L"string"s to const std::wstring& function parameters and the wstring
constructor gets inlined.

This also fixes a lingerind API problem/bug in getConstantStringInfo()
where zeroinitializers would always give you an empty string (without a
length) back regardless of the actual length of the initializer which
did not work well in the TrimAtNul==false causing the PR mentioned
below.

Note that the fixed getConstantStringInfo() needed fixes to SelectionDAG
memcpy lowering and may lead to some cases for out-of-bounds
zeroinitializer accesses not getting optimized anymore. So some code
with UB may produce out of bound memory reads now instead of just
producing zeros.

The refactoring "accidentally" fixes http://llvm.org/PR32124

Differential Revision: https://reviews.llvm.org/D32839

llvm-svn: 303461
 2017-05-19 22:37:09 +00:00
Sanjay Patel 0d0181006a [InstCombine] regenerate checks 
llvm-svn: 268244
 2016-05-02 15:25:49 +00:00
Benjamin Kramer d6aa0ec737 [SimplifyLibCalls] Fix negative shifts being produced by the memchr -> bitfield transform. 
llvm-svn: 232903
 2015-03-21 22:04:26 +00:00
Benjamin Kramer 7857d723f1 [SimplifyLibCalls] Turn memchr(const, C, const) into a bitfield check. 
strchr("123!", C) != nullptr is a common pattern to check if C is one
of 1, 2, 3 or !. If the largest element of the string is smaller than
the target's register size we can easily create a bitfield and just
do a simple test for set membership.

int foo(char C) { return strchr("123!", C) != nullptr; } now becomes

	cmpl	$64, %edi ## range check
	sbbb	%al, %al
	movabsq	$0xE000200000001, %rcx
	btq	%rdi, %rcx ## bit test
	sbbb	%cl, %cl
	andb	%al, %cl ## and the two conditions
	andb	$1, %cl
	movzbl	%cl, %eax ## returning an int
	ret

(imho the backend should expand this into a series of branches, but
that's a different story)

The code is currently limited to bit fields that fit in a register, so
usually 64 or 32 bits. Sadly, this misses anything using alpha chars
or {}. This could be fixed by just emitting a i128 bit field, but that
can generate really ugly code so we have to find a better way. To some
degree this is also recreating switch lowering logic, but we can't
simply emit a switch instruction and thus change the CFG within
instcombine.

llvm-svn: 232902
 2015-03-21 21:09:33 +00:00
Benjamin Kramer 691363e7f2 SimplifyLibCalls: Add basic optimization of memchr calls. 
This is just memchr(x, y, 0) -> nullptr and constant folding.

llvm-svn: 232896
 2015-03-21 15:36:21 +00:00