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Author SHA1 Message Date
Reid Kleckner fbd5eef691 Revert "InstCombine rule to fold trunc when value available" 
This reverts commit r273608.

Broke building code with sanitizers, where apparently these kinds of
loads, casts, and truncations are common:

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/24502
http://crbug.com/623099

llvm-svn: 273703
 2016-06-24 18:42:58 +00:00
Anna Thomas 31a0b2088f InstCombine rule to fold trunc when value available 
Summary:
This instcombine rule folds away trunc operations that have value available from a prior load or store.
This kind of code can be generated as a result of GVN widening the load or from source code as well.

Reviewers: reames, majnemer, sanjoy

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21246

llvm-svn: 273608
 2016-06-23 20:22:22 +00:00
Matt Arsenault a466a7cf62 Add looping testcase that broke in r272987 
llvm-svn: 273081
 2016-06-18 05:15:58 +00:00
Matt Arsenault 8fd5978811 Revert "Revert "Revert "InstCombine: Reduce trunc (shl x, K) width.""" 
This seems to be causing an infinite loop / crash in instcombine
on some bots.

llvm-svn: 273069
 2016-06-17 23:36:38 +00:00
Matt Arsenault d76efc14b9 Revert "Revert "InstCombine: Reduce trunc (shl x, K) width."" 
Reapply r272987. Condition should be in terms of the destination type,
and the flags should not be copied.

llvm-svn: 273045
 2016-06-17 20:33:53 +00:00
Matt Arsenault ce56f7bbaa Revert "InstCombine: Reduce trunc (shl x, K) width." 
This reverts commit r272987.

This might be causing crashes on some bots.

llvm-svn: 272990
 2016-06-17 06:28:53 +00:00
Matt Arsenault 028fd50642 InstCombine: Reduce trunc (shl x, K) width. 
llvm-svn: 272987
 2016-06-17 04:43:22 +00:00
Sanjay Patel f727e387be [InstCombine] fold trunc ([lshr] (bitcast vector) ) --> extractelement (PR25543) 
This is a fix for PR25543:
https://llvm.org/bugs/show_bug.cgi?id=25543

The idea is to take the existing fold of:
bitcast ( trunc ( lshr ( bitcast X))) --> extractelement (bitcast X)
( http://reviews.llvm.org/rL112232 )

And break it into less specific transforms so we'll catch more cases such as
the example in the bug report:
bitcast ( trunc ( lshr ( bitcast X))) -->
bitcast ( extractelement (bitcast X)) -->
extractelement (bitcast X)

Enabling patches for this change:
http://reviews.llvm.org/rL255399 (combine bitcasts)
http://reviews.llvm.org/rL255433 (canonicalize extractelement(bitcast X))

Differential Revision: http://reviews.llvm.org/D15392

llvm-svn: 255504
 2015-12-14 16:16:54 +00:00
Sanjay Patel c4aa50414b [InstCombine] add tests to show missing trunc optimizations 
llvm-svn: 253609
 2015-11-19 22:11:52 +00:00
Stephen Lin c1c7a1309c Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. 
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186268
 2013-07-14 01:42:54 +00:00
Jakob Stoklund Olesen c5c4e96f3e Revert remaining part of r93200: "Disable folding sext(trunc(x)) -> x" 
This fixes PR5997.

These transforms were disabled because codegen couldn't deal with other
uses of trunc(x). This is now handled by the peephole pass.

This causes no regressions on x86-64.

llvm-svn: 159003
 2012-06-22 16:36:43 +00:00
Chris Lattner 6b657aed33 Enhance a bunch of transformations in instcombine to start generating 
exact/nsw/nuw shifts and have instcombine infer them when it can prove
that the relevant properties are true for a given shift without them.

Also, a variety of refactoring to use the new patternmatch logic thrown
in for good luck.  I believe that this takes care of a bunch of related
code quality issues attached to PR8862.

llvm-svn: 125267
 2011-02-10 05:36:31 +00:00
Chris Lattner 9c10d587f6 implement an instcombine xform that canonicalizes casts outside of and-with-constant operations. 
This fixes rdar://8808586 which observed that we used to compile:


union xy {
        struct x { _Bool b[15]; } x;
        __attribute__((packed))
        struct y {
                __attribute__((packed)) unsigned long b0to7;
                __attribute__((packed)) unsigned int b8to11;
                __attribute__((packed)) unsigned short b12to13;
                __attribute__((packed)) unsigned char b14;
        } y;
};

struct x
foo(union xy *xy)
{
        return xy->x;
}

into:

_foo:                                   ## @foo
	movq	(%rdi), %rax
	movabsq	$1095216660480, %rcx    ## imm = 0xFF00000000
	andq	%rax, %rcx
	movabsq	$-72057594037927936, %rdx ## imm = 0xFF00000000000000
	andq	%rax, %rdx
	movzbl	%al, %esi
	orq	%rdx, %rsi
	movq	%rax, %rdx
	andq	$65280, %rdx            ## imm = 0xFF00
	orq	%rsi, %rdx
	movq	%rax, %rsi
	andq	$16711680, %rsi         ## imm = 0xFF0000
	orq	%rdx, %rsi
	movl	%eax, %edx
	andl	$-16777216, %edx        ## imm = 0xFFFFFFFFFF000000
	orq	%rsi, %rdx
	orq	%rcx, %rdx
	movabsq	$280375465082880, %rcx  ## imm = 0xFF0000000000
	movq	%rax, %rsi
	andq	%rcx, %rsi
	orq	%rdx, %rsi
	movabsq	$71776119061217280, %r8 ## imm = 0xFF000000000000
	andq	%r8, %rax
	orq	%rsi, %rax
	movzwl	12(%rdi), %edx
	movzbl	14(%rdi), %esi
	shlq	$16, %rsi
	orl	%edx, %esi
	movq	%rsi, %r9
	shlq	$32, %r9
	movl	8(%rdi), %edx
	orq	%r9, %rdx
	andq	%rdx, %rcx
	movzbl	%sil, %esi
	shlq	$32, %rsi
	orq	%rcx, %rsi
	movl	%edx, %ecx
	andl	$-16777216, %ecx        ## imm = 0xFFFFFFFFFF000000
	orq	%rsi, %rcx
	movq	%rdx, %rsi
	andq	$16711680, %rsi         ## imm = 0xFF0000
	orq	%rcx, %rsi
	movq	%rdx, %rcx
	andq	$65280, %rcx            ## imm = 0xFF00
	orq	%rsi, %rcx
	movzbl	%dl, %esi
	orq	%rcx, %rsi
	andq	%r8, %rdx
	orq	%rsi, %rdx
	ret

We now compile this into:

_foo:                                   ## @foo
## BB#0:                                ## %entry
	movzwl	12(%rdi), %eax
	movzbl	14(%rdi), %ecx
	shlq	$16, %rcx
	orl	%eax, %ecx
	shlq	$32, %rcx
	movl	8(%rdi), %edx
	orq	%rcx, %rdx
	movq	(%rdi), %rax
	ret

A small improvement :-)

llvm-svn: 123520
 2011-01-15 06:32:33 +00:00
Chris Lattner 7398434675 teach the truncation optimization that an entire chain of 
computation can be truncated if it is fed by a sext/zext that doesn't
have to be exactly equal to the truncation result type.

llvm-svn: 112285
 2010-08-27 20:32:06 +00:00
Chris Lattner 90cd746e63 Add an instcombine to clean up a common pattern produced 
by the SRoA "promote to large integer" code, eliminating
some type conversions like this:

   %94 = zext i16 %93 to i32                       ; <i32> [#uses=2]
   %96 = lshr i32 %94, 8                           ; <i32> [#uses=1]
   %101 = trunc i32 %96 to i8                      ; <i8> [#uses=1]

This also unblocks other xforms from happening, now clang is able to compile:

struct S { float A, B, C, D; };
float foo(struct S A) { return A.A + A.B+A.C+A.D; }

into:

_foo:                                   ## @foo
## BB#0:                                ## %entry
	pshufd	$1, %xmm0, %xmm2
	addss	%xmm0, %xmm2
	movdqa	%xmm1, %xmm3
	addss	%xmm2, %xmm3
	pshufd	$1, %xmm1, %xmm0
	addss	%xmm3, %xmm0
	ret

on x86-64, instead of:

_foo:                                   ## @foo
## BB#0:                                ## %entry
	movd	%xmm0, %rax
	shrq	$32, %rax
	movd	%eax, %xmm2
	addss	%xmm0, %xmm2
	movapd	%xmm1, %xmm3
	addss	%xmm2, %xmm3
	movd	%xmm1, %rax
	shrq	$32, %rax
	movd	%eax, %xmm0
	addss	%xmm3, %xmm0
	ret

This seems pretty close to optimal to me, at least without
using horizontal adds.  This also triggers in lots of other
code, including SPEC.

llvm-svn: 112278
 2010-08-27 18:31:05 +00:00
Chris Lattner c188b96bbe filecheckize 
llvm-svn: 112235
 2010-08-26 22:23:39 +00:00
Chris Lattner 387d6bcdcb rename test. 
llvm-svn: 112234
 2010-08-26 22:20:47 +00:00