Commit Graph

43 Commits

Author SHA1 Message Date
Pete Cooper 67cf9a723b Revert "Change memcpy/memset/memmove to have dest and source alignments."
This reverts commit r253511.

This likely broke the bots in
http://lab.llvm.org:8011/builders/clang-ppc64-elf-linux2/builds/20202
http://bb.pgr.jp/builders/clang-3stage-i686-linux/builds/3787

llvm-svn: 253543
2015-11-19 05:56:52 +00:00
Pete Cooper 72bc23ef02 Change memcpy/memset/memmove to have dest and source alignments.
Note, this was reviewed (and more details are in) http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

These intrinsics currently have an explicit alignment argument which is
required to be a constant integer.  It represents the alignment of the
source and dest, and so must be the minimum of those.

This change allows source and dest to each have their own alignments
by using the alignment attribute on their arguments.  The alignment
argument itself is removed.

There are a few places in the code for which the code needs to be
checked by an expert as to whether using only src/dest alignment is
safe.  For those places, they currently take the minimum of src/dest
alignments which matches the current behaviour.

For example, code which used to read:
  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 500, i32 8, i1 false)
will now read:
  call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 8 %dest, i8* align 8 %src, i32 500, i1 false)

For out of tree owners, I was able to strip alignment from calls using sed by replacing:
  (call.*llvm\.memset.*)i32\ [0-9]*\,\ i1 false\)
with:
  $1i1 false)

and similarly for memmove and memcpy.

I then added back in alignment to test cases which needed it.

A similar commit will be made to clang which actually has many differences in alignment as now
IRBuilder can generate different source/dest alignments on calls.

In IRBuilder itself, a new argument was added.  Instead of calling:
  CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, /* isVolatile */ false)
you now call
  CreateMemCpy(Dst, Src, getInt64(Size), DstAlign, SrcAlign, /* isVolatile */ false)

There is a temporary class (IntegerAlignment) which takes the source alignment and rejects
implicit conversion from bool.  This is to prevent isVolatile here from passing its default
parameter to the source alignment.

Note, changes in future can now be made to codegen.  I didn't change anything here, but this
change should enable better memcpy code sequences.

Reviewed by Hal Finkel.

llvm-svn: 253511
2015-11-18 22:17:24 +00:00
David Blaikie 23af64846f [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction
See r230786 and r230794 for similar changes to gep and load
respectively.

Call is a bit different because it often doesn't have a single explicit
type - usually the type is deduced from the arguments, and just the
return type is explicit. In those cases there's no need to change the
IR.

When that's not the case, the IR usually contains the pointer type of
the first operand - but since typed pointers are going away, that
representation is insufficient so I'm just stripping the "pointerness"
of the explicit type away.

This does make the IR a bit weird - it /sort of/ reads like the type of
the first operand: "call void () %x(" but %x is actually of type "void
()*" and will eventually be just of type "ptr". But this seems not too
bad and I don't think it would benefit from repeating the type
("void (), void () * %x(" and then eventually "void (), ptr %x(") as has
been done with gep and load.

This also has a side benefit: since the explicit type is no longer a
pointer, there's no ambiguity between an explicit type and a function
that returns a function pointer. Previously this case needed an explicit
type (eg: a function returning a void() function was written as
"call void () () * @x(" rather than "call void () * @x(" because of the
ambiguity between a function returning a pointer to a void() function
and a function returning void).

No ambiguity means even function pointer return types can just be
written alone, without writing the whole function's type.

This leaves /only/ the varargs case where the explicit type is required.

Given the special type syntax in call instructions, the regex-fu used
for migration was a bit more involved in its own unique way (as every
one of these is) so here it is. Use it in conjunction with the apply.sh
script and associated find/xargs commands I've provided in rr230786 to
migrate your out of tree tests. Do let me know if any of this doesn't
cover your cases & we can iterate on a more general script/regexes to
help others with out of tree tests.

About 9 test cases couldn't be automatically migrated - half of those
were functions returning function pointers, where I just had to manually
delete the function argument types now that we didn't need an explicit
function type there. The other half were typedefs of function types used
in calls - just had to manually drop the * from those.

import fileinput
import sys
import re

pat = re.compile(r'((?:=|:|^|\s)call\s(?:[^@]*?))(\s*$|\s*(?:(?:\[\[[a-zA-Z0-9_]+\]\]|[@%](?:(")?[\\\?@a-zA-Z0-9_.]*?(?(3)"|)|{{.*}}))(?:\(|$)|undef|inttoptr|bitcast|null|asm).*$)')
addrspace_end = re.compile(r"addrspace\(\d+\)\s*\*$")
func_end = re.compile("(?:void.*|\)\s*)\*$")

def conv(match, line):
  if not match or re.search(addrspace_end, match.group(1)) or not re.search(func_end, match.group(1)):
    return line
  return line[:match.start()] + match.group(1)[:match.group(1).rfind('*')].rstrip() + match.group(2) + line[match.end():]

for line in sys.stdin:
  sys.stdout.write(conv(re.search(pat, line), line))

llvm-svn: 235145
2015-04-16 23:24:18 +00:00
David Blaikie a79ac14fa6 [opaque pointer type] Add textual IR support for explicit type parameter to load instruction
Essentially the same as the GEP change in r230786.

A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)

import fileinput
import sys
import re

pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")

for line in sys.stdin:
  sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7649

llvm-svn: 230794
2015-02-27 21:17:42 +00:00
David Blaikie 79e6c74981 [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction
One of several parallel first steps to remove the target type of pointers,
replacing them with a single opaque pointer type.

This adds an explicit type parameter to the gep instruction so that when the
first parameter becomes an opaque pointer type, the type to gep through is
still available to the instructions.

* This doesn't modify gep operators, only instructions (operators will be
  handled separately)

* Textual IR changes only. Bitcode (including upgrade) and changing the
  in-memory representation will be in separate changes.

* geps of vectors are transformed as:
    getelementptr <4 x float*> %x, ...
  ->getelementptr float, <4 x float*> %x, ...
  Then, once the opaque pointer type is introduced, this will ultimately look
  like:
    getelementptr float, <4 x ptr> %x
  with the unambiguous interpretation that it is a vector of pointers to float.

* address spaces remain on the pointer, not the type:
    getelementptr float addrspace(1)* %x
  ->getelementptr float, float addrspace(1)* %x
  Then, eventually:
    getelementptr float, ptr addrspace(1) %x

Importantly, the massive amount of test case churn has been automated by
same crappy python code. I had to manually update a few test cases that
wouldn't fit the script's model (r228970,r229196,r229197,r229198). The
python script just massages stdin and writes the result to stdout, I
then wrapped that in a shell script to handle replacing files, then
using the usual find+xargs to migrate all the files.

update.py:
import fileinput
import sys
import re

ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")
normrep = re.compile(       r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")

def conv(match, line):
  if not match:
    return line
  line = match.groups()[0]
  if len(match.groups()[5]) == 0:
    line += match.groups()[2]
  line += match.groups()[3]
  line += ", "
  line += match.groups()[1]
  line += "\n"
  return line

for line in sys.stdin:
  if line.find("getelementptr ") == line.find("getelementptr inbounds"):
    if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("):
      line = conv(re.match(ibrep, line), line)
  elif line.find("getelementptr ") != line.find("getelementptr ("):
    line = conv(re.match(normrep, line), line)
  sys.stdout.write(line)

apply.sh:
for name in "$@"
do
  python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
  rm -f "$name.tmp"
done

The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh

After that, check-all (with llvm, clang, clang-tools-extra, lld,
compiler-rt, and polly all checked out).

The extra 'rm' in the apply.sh script is due to a few files in clang's test
suite using interesting unicode stuff that my python script was throwing
exceptions on. None of those files needed to be migrated, so it seemed
sufficient to ignore those cases.

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7636

llvm-svn: 230786
2015-02-27 19:29:02 +00:00
Mehdi Amini 945a660cbc Change the fast-isel-abort option from bool to int to enable "levels"
Summary:
Currently fast-isel-abort will only abort for regular instructions,
and just warn for function calls, terminators, function arguments.
There is already fast-isel-abort-args but nothing for calls and
terminators.

This change turns the fast-isel-abort options into an integer option,
so that multiple levels of strictness can be defined.
This will help no being surprised when the "abort" option indeed does
not abort, and enables the possibility to write test that verifies
that no intrinsics are forgotten by fast-isel.

Reviewers: resistor, echristo

Subscribers: jfb, llvm-commits

Differential Revision: http://reviews.llvm.org/D7941

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 230775
2015-02-27 18:32:11 +00:00
Derek Schuff a54222045e [x86 fast-isel] Materialize allocas with the correct-sized lea for ILP32
Summary:
X86FastISel::fastMaterializeAlloca was incorrectly conditioning its
opcode selection on subtarget bitness rather than pointer size.

Differential Revision: http://reviews.llvm.org/D6136

llvm-svn: 221386
2014-11-05 19:27:21 +00:00
Juergen Ributzka 89d187b387 Reapply [FastISel][X86] Use XOR to materialize the "0" value (r215594).
Note: This was originally reverted to track down a buildbot error. Reapply
without any modifications.

llvm-svn: 216011
2014-08-19 19:44:10 +00:00
Juergen Ributzka 4bf6c01cdb Reapply [FastISel] Let the target decide first if it wants to materialize a constant (215588).
Note: This was originally reverted to track down a buildbot error. This commit
exposed a latent bug that was fixed in r215753. Therefore it is reapplied
without any modifications.

I run it through SPEC2k and SPEC2k6 for AArch64 and it didn't introduce any new
regeressions.

Original commit message:
This changes the order in which FastISel tries to materialize a constant.
Originally it would try to use a simple target-independent approach, which
can lead to the generation of inefficient code.

On X86 this would result in the use of movabsq to materialize any 64bit
integer constant - even for simple and small values such as 0 and 1. Also
some very funny floating-point materialization could be observed too.

On AArch64 it would materialize the constant 0 in a register even the
architecture has an actual "zero" register.

On ARM it would generate unnecessary mov instructions or not use mvn.

This change simply changes the order and always asks the target first if it
likes to materialize the constant. This doesn't fix all the issues
mentioned above, but it enables the targets to implement such
optimizations.

Related to <rdar://problem/17420988>.

llvm-svn: 216006
2014-08-19 19:05:24 +00:00
Juergen Ributzka 790bacf232 Revert several FastISel commits to track down a buildbot error.
This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."

llvm-svn: 215673
2014-08-14 19:56:28 +00:00
Juergen Ributzka ba8b79e932 [FastISel][X86] Use XOR to materialize the "0" value.
llvm-svn: 215594
2014-08-13 22:22:17 +00:00
Juergen Ributzka 7cee768e55 [FastISel] Let the target decide first if it wants to materialize a constant.
This changes the order in which FastISel tries to materialize a constant.
Originally it would try to use a simple target-independent approach, which
can lead to the generation of inefficient code.

On X86 this would result in the use of movabsq to materialize any 64bit
integer constant - even for simple and small values such as 0 and 1. Also
some very funny floating-point materialization could be observed too.

On AArch64 it would materialize the constant 0 in a register even the
architecture has an actual "zero" register.

On ARM it would generate unnecessary mov instructions or not use mvn.

This change simply changes the order and always asks the target first if it
likes to materialize the constant. This doesn't fix all the issues
mentioned above, but it enables the targets to implement such
optimizations.

Related to <rdar://problem/17420988>.

llvm-svn: 215588
2014-08-13 22:08:02 +00:00
Stephen Lin f799e3f944 Convert CodeGen/*/*.ll tests to use the new CHECK-LABEL for easier debugging. No functionality change and all tests pass after conversion.
This was done with the following sed invocation to catch label lines demarking function boundaries:
    sed -i '' "s/^;\( *\)\([A-Z0-9_]*\):\( *\)test\([A-Za-z0-9_-]*\):\( *\)$/;\1\2-LABEL:\3test\4:\5/g" test/CodeGen/*/*.ll
which was written conservatively to avoid false positives rather than false negatives. I scanned through all the changes and everything looks correct.

llvm-svn: 186258
2013-07-13 20:38:47 +00:00
Preston Gurd a01daace88 Pad Short Functions for Intel Atom
The current Intel Atom microarchitecture has a feature whereby
when a function returns early then it is slightly faster to execute
a sequence of NOP instructions to wait until the return address is ready,
as opposed to simply stalling on the ret instruction until
the return address is ready.

When compiling for X86 Atom only, this patch will run a pass,
called "X86PadShortFunction" which will add NOP instructions where less
than four cycles elapse between function entry and return.

It includes tests.

This patch has been updated to address Nadav's review comments
- Optimize only at >= O1 and don't do optimization if -Os is set
- Stores MachineBasicBlock* instead of BBNum
- Uses DenseMap instead of std::map
- Fixes placement of braces

Patch by Andy Zhang.

llvm-svn: 171879
2013-01-08 18:27:24 +00:00
Nadav Rotem 478b6a47ec Revert revision 171524. Original message:
URL: http://llvm.org/viewvc/llvm-project?rev=171524&view=rev
Log:
The current Intel Atom microarchitecture has a feature whereby when a function
returns early then it is slightly faster to execute a sequence of NOP
instructions to wait until the return address is ready,
as opposed to simply stalling on the ret instruction
until the return address is ready.

When compiling for X86 Atom only, this patch will run a pass, called
"X86PadShortFunction" which will add NOP instructions where less than four
cycles elapse between function entry and return.

It includes tests.

Patch by Andy Zhang.

llvm-svn: 171603
2013-01-05 05:42:48 +00:00
Preston Gurd e36b685a94 The current Intel Atom microarchitecture has a feature whereby when a function
returns early then it is slightly faster to execute a sequence of NOP
instructions to wait until the return address is ready,
as opposed to simply stalling on the ret instruction
until the return address is ready.

When compiling for X86 Atom only, this patch will run a pass, called
"X86PadShortFunction" which will add NOP instructions where less than four
cycles elapse between function entry and return.

It includes tests.

Patch by Andy Zhang.

llvm-svn: 171524
2013-01-04 20:54:54 +00:00
Nick Lewycky f8fc892b6c Make sure to put our sret argument into %rax on x86-64. Fixes PR13563!
llvm-svn: 165063
2012-10-02 22:45:06 +00:00
Michael Liao bbd10792c2 Introduce 'UseSSEx' to force SSE legacy encoding
- Add 'UseSSEx' to force SSE legacy insn not being selected when AVX is
  enabled.

  As the penalty of inter-mixing SSE and AVX instructions, we need
  prevent SSE legacy insn from being generated except explicitly
  specified through some intrinsics. For patterns supported by both
  SSE and AVX, so far, we force AVX insn will be tried first relying on
  AddedComplexity or position in td file. It's error-prone and
  introduces bugs accidentally.

  'UseSSEx' is disabled when AVX is turned on. For SSE insns inherited
  by AVX, we need this predicate to force VEX encoding or SSE legacy
  encoding only.

  For insns not inherited by AVX, we still use the previous predicates,
  i.e. 'HasSSEx'. So far, these insns fall into the following
  categories:
  * SSE insns with MMX operands
  * SSE insns with GPR/MEM operands only (xFENCE, PREFETCH, CLFLUSH,
    CRC, and etc.)
  * SSE4A insns.
  * MMX insns.
  * x87 insns added by SSE.

2 test cases are modified:

 - test/CodeGen/X86/fast-isel-x86-64.ll
   AVX code generation is different from SSE one. 'vcvtsi2sdq' cannot be
   selected by fast-isel due to complicated pattern and fast-isel
   fallback to materialize it from constant pool.

 - test/CodeGen/X86/widen_load-1.ll
   AVX code generation is different from SSE one after fixing SSE/AVX
   inter-mixing. Exec-domain fixing prefers 'vmovapd' instead of
   'vmovaps'.

llvm-svn: 162919
2012-08-30 16:54:46 +00:00
Jakob Stoklund Olesen bde32d36bb Make X86::FsFLD0SS / FsFLD0SD real pseudo-instructions.
Like V_SET0, these instructions are expanded by ExpandPostRA to xorps /
vxorps so they can participate in execution domain swizzling.

This also makes the AVX variants redundant.

llvm-svn: 145440
2011-11-29 22:27:25 +00:00
Evan Cheng 822ddde50d Disable expensive two-address optimizations at -O0. rdar://10453055
llvm-svn: 144806
2011-11-16 18:44:48 +00:00
Ivan Krasin d7cbd4c518 FastISel: avoid function calls between the materialization of the constant and its use.
llvm-svn: 137993
2011-08-18 22:06:10 +00:00
Eli Friedman 7cd5101ad3 fast-isel sret calls, try 2. We actually do need to do something on x86-32. rdar://problem/9303592 .
llvm-svn: 130429
2011-04-28 20:19:12 +00:00
Eli Friedman 3cf6d4032a Actually revert r130348 correctly.
llvm-svn: 130418
2011-04-28 18:20:24 +00:00
Eli Friedman d5a80ca3c8 Revert r130348; causing buildbot issues on x86-32.
llvm-svn: 130412
2011-04-28 18:06:10 +00:00
Eli Friedman 33c133919a Fix a silly mistake in r130338.
llvm-svn: 130360
2011-04-28 00:42:03 +00:00
Eli Friedman 8bd572fc58 fast-isel sret. We actually don't need to do anything special on x86. :) rdar://problem/9303592 .
llvm-svn: 130348
2011-04-27 23:58:52 +00:00
Eli Friedman 406c471b69 Make the fast-isel code for literal 0.0 a bit shorter/faster, since 0.0 is common. rdar://problem/9303592 .
llvm-svn: 130338
2011-04-27 22:41:55 +00:00
Chris Lattner 6d277517d1 Recommit the fix for rdar://9289512 with a couple tweaks to
fix bugs exposed by the gcc dejagnu testsuite:
1. The load may actually be used by a dead instruction, which
   would cause an assert.
2. The load may not be used by the current chain of instructions,
   and we could move it past a side-effecting instruction. Change
   how we process uses to define the problem away.

llvm-svn: 130018
2011-04-22 21:59:37 +00:00
Daniel Dunbar 6309828206 Revert r1296656, "Fix rdar://9289512 - not folding load into compare at -O0...",
which broke a couple GCC test suite tests at -O0.

llvm-svn: 129914
2011-04-21 16:14:46 +00:00
Eli Friedman ee92a6b332 Add support for FastISel'ing varargs calls.
llvm-svn: 129765
2011-04-19 17:22:22 +00:00
Chris Lattner 91328b317b Implement support for x86 fastisel of small fixed-sized memcpys, which are generated
en-mass for C++ PODs.  On my c++ test file, this cuts the fast isel rejects by 10x 
and shrinks the generated .s file by 5%

llvm-svn: 129755
2011-04-19 05:52:03 +00:00
Chris Lattner 5f4b783426 Implement support for fast isel of calls of i1 arguments, even though they are illegal,
when they are a truncate from something else.  This eliminates fully half of all the 
fastisel rejections on a test c++ file I'm working with, which should make a substantial
improvement for -O0 compile of c++ code.

This fixed rdar://9297003 - fast isel bails out on all functions taking bools

llvm-svn: 129752
2011-04-19 05:09:50 +00:00
Chris Lattner d7f7c93914 Handle i1/i8/i16 constant integer arguments to calls by prepromoting them.
Before we would bail out on i1 arguments all together, now we just bail on
non-constant ones.  Also, we used to emit extraneous code.  e.g. test12 was:

	movb	$0, %al
	movzbl	%al, %edi
	callq	_test12

and test13 was:
	movb	$0, %al
	xorl	%edi, %edi
	movb	%al, 7(%rsp)
	callq	_test13f

Now we get:

	movl	$0, %edi
	callq	_test12
and:
	movl	$0, %edi
	callq	_test13f

llvm-svn: 129751
2011-04-19 04:42:38 +00:00
Chris Lattner c59290a34c be layout aware, to produce:
testb	$1, %al
	je	LBB0_2
## BB#1:                                ## %if.then
	movb	$0, %al

instead of:

	testb	$1, %al
	jne	LBB0_1
	jmp	LBB0_2
LBB0_1:                                 ## %if.then
	movb	$0, %al

how 'bout that.

llvm-svn: 129749
2011-04-19 04:26:32 +00:00
Chris Lattner 2c8a4c3b1b fix rdar://9297006 - fast isel bails out on trunc to i1 -> bools cry,
a common cause of fast isel rejects on c++ code.

llvm-svn: 129748
2011-04-19 04:22:17 +00:00
Chris Lattner 48f75ad678 while we're at it, handle 'sdiv exact' of a power of 2 also,
this fixes a few rejects on c++ iterator loops.

llvm-svn: 129694
2011-04-18 07:00:40 +00:00
Chris Lattner 562d6e82bd fix rdar://9297011 - udiv by power of two causing fast-isel rejects
llvm-svn: 129693
2011-04-18 06:55:51 +00:00
Chris Lattner 07add49a4b Implement major new fastisel functionality: the matcher can now handle immediates with
value constraints on them (when defined as ImmLeaf's).  This is particularly important
for X86-64, where almost all reg/imm instructions take a i64immSExt32 immediate operand,
which has a value constraint.  Before this patch we ended up iseling the examples into
such amazing code as:

	movabsq	$7, %rax
	imulq	%rax, %rdi
	movq	%rdi, %rax
	ret

now we produce:

	imulq	$7, %rdi, %rax
	ret

This dramatically shrinks the generated code at -O0 on x86-64.

llvm-svn: 129691
2011-04-18 06:22:33 +00:00
Chris Lattner b53ccb8e36 1. merge fast-isel-shift-imm.ll into fast-isel-x86-64.ll
2. implement rdar://9289501 - fast isel should fold trivial multiplies to shifts
3. teach tblgen to handle shift immediates that are different sizes than the 
   shifted operands, eliminating some code from the X86 fast isel backend.
4. Have FastISel::SelectBinaryOp use (the poorly named) FastEmit_ri_ function
   instead of FastEmit_ri to simplify code.

llvm-svn: 129666
2011-04-17 20:23:29 +00:00
Chris Lattner eb729d48ff fix an x86 fast isel issue where we'd completely give up on folding an address
when we have a global variable base an an index.  Instead, just give up on
folding the global variable.

Before we'd geenrate:

_test:                                  ## @test
## BB#0:
	movq	_rtx_length@GOTPCREL(%rip), %rax
	leaq	(%rax), %rax
	addq	%rdi, %rax
	movzbl	(%rax), %eax
	ret

now we generate:

_test:                                  ## @test
## BB#0:
	movq	_rtx_length@GOTPCREL(%rip), %rax
	movzbl	(%rax,%rdi), %eax
	ret

The difference is even more significant when there is a scale
involved.

This fixes rdar://9289558 - total fail with addr mode formation at -O0/x86-64

llvm-svn: 129664
2011-04-17 17:47:38 +00:00
Chris Lattner 4832660b4d fix an oversight which caused us to compile the testcase (and other
less trivial things) into a dummy lea.  Before we generated:

_test:                                  ## @test
	movq	_G@GOTPCREL(%rip), %rax
	leaq	(%rax), %rax
	ret

now we produce:

_test:                                  ## @test
	movq	_G@GOTPCREL(%rip), %rax
	ret

This is part of rdar://9289558

llvm-svn: 129662
2011-04-17 17:12:08 +00:00
Chris Lattner 045c43855c Fix rdar://9289512 - not folding load into compare at -O0
The basic issue here is that bottom-up isel is matching the branch
and compare, and was failing to fold the load into the branch/compare
combo.  Fixing this (by allowing folding into any instruction of a
sequence that is selected) allows us to produce things like:


cmpb    $0, 52(%rax)
je      LBB4_2

instead of:

movb    52(%rax), %cl
cmpb    $0, %cl
je      LBB4_2

This makes the generated -O0 code run a bit faster, but also speeds up
compile time by putting less pressure on the register allocator and 
generating less code.

This was one of the biggest classes of missing load folding.  Implementing
this shrinks 176.gcc's c-decl.s (as a random example) by about 4% in (verbose-asm)
line count.

llvm-svn: 129656
2011-04-17 06:35:44 +00:00
Chris Lattner fba7ca63cc fix rdar://9289583 - fast isel should handle non-canonical commutative binops
allowing us to fold the immediate into the 'and' in this case:

int test1(int i) {
  return 8&i;
}

llvm-svn: 129653
2011-04-17 01:16:47 +00:00