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* Add two notes for correlated-expression optimizations.Benjamin Kramer2011-09-071-0/+10
| | | | git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139263 91177308-0d34-0410-b5e6-96231b3b80d8
* Don't emit a bit test if there is only one case the test can yield false. A ↵Benjamin Kramer2011-07-141-9/+4
| | | | | | simple SETNE is sufficient. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135126 91177308-0d34-0410-b5e6-96231b3b80d8
* InstCombine: Fold A-b == C --> b == A-C if A and C are constants.Benjamin Kramer2011-06-131-5/+0
| | | | | | The backend already knew this trick. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132915 91177308-0d34-0410-b5e6-96231b3b80d8
* clarify this, apparently it is confusing :)Chris Lattner2011-05-231-1/+3
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* add a note.Chris Lattner2011-05-221-0/+10
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* move PR9408 here.Chris Lattner2011-05-221-0/+40
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* Transform: "icmp eq (trunc (lshr(X, cst1)), cst" to "icmp (and X, mask), cst"Chris Lattner2011-04-261-46/+0
| | | | | | | | | | | | when X has multiple uses. This is useful for exposing secondary optimizations, but the X86 backend isn't ready for this when X has a single use. For example, this can disable load folding. This is inching towards resolving PR6627. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130238 91177308-0d34-0410-b5e6-96231b3b80d8
* add a missed bitfield instcombine.Chris Lattner2011-04-251-0/+47
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* DAGCombine: fold "(zext x) == C" into "x == (trunc C)" if the trunc is lossless.Benjamin Kramer2011-04-221-30/+1
| | | | | | | | | | | | On x86 this allows to fold a load into the cmp, greatly reducing register pressure. movzbl (%rdi), %eax cmpl $47, %eax -> cmpb $47, (%rdi) This shaves 8k off gcc.o on i386. I'll leave applying the patch in README.txt to Chris :) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130005 91177308-0d34-0410-b5e6-96231b3b80d8
* add a minor missed dag combine that is blocking mid-level optimizationChris Lattner2011-04-141-0/+76
| | | | | | | | improvements, that will lead to fixing PR6627. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129504 91177308-0d34-0410-b5e6-96231b3b80d8
* Add a note.Benjamin Kramer2011-03-251-0/+19
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* A bit more analysis of a memset-related README entry.Eli Friedman2011-03-221-4/+5
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* This README entry was fixed recently.Eli Friedman2011-03-211-28/+0
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* add a noteChris Lattner2011-03-011-0/+15
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* Add some DAGCombines for (adde 0, 0, glue), which are useful to optimize ↵Benjamin Kramer2011-02-261-37/+0
| | | | | | | | | | | legalized code for large integer arithmetic. 1. Inform users of ADDEs with two 0 operands that it never sets carry 2. Fold other ADDs or ADDCs into the ADDE if possible It would be neat if we could do the same thing for SETCC+ADD eventually, but we can't do that in target independent code. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126557 91177308-0d34-0410-b5e6-96231b3b80d8
* add a missed loop deletion case.Chris Lattner2011-02-211-0/+14
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* add an idiom that loop idiom could theoretically catch.Chris Lattner2011-02-211-0/+10
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* This has been implemented.Duncan Sands2011-02-171-10/+0
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* add some notes on compares + binops. Remove redundant entries.Chris Lattner2011-02-171-20/+47
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* Add a few missed xforms from GCC PR14753Chris Lattner2011-02-161-0/+29
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* Remove outdated README entry.Eli Friedman2011-02-161-12/+0
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* Remove outdated README entry.Eli Friedman2011-02-161-16/+0
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* Update README entry.Eli Friedman2011-02-161-13/+6
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* Remove a virtual inheritance case that clang can devirtualize fully now.Anders Carlsson2011-02-061-21/+0
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* SimplifyCFG: Turn switches into sub+icmp+branch if possible.Benjamin Kramer2011-02-021-48/+0
| | | | | | | | | | | | | | | | | This makes the job of the later optzn passes easier, allowing the vast amount of icmp transforms to chew on it. We transform 840 switches in gcc.c, leading to a 16k byte shrink of the resulting binary on i386-linux. The testcase from README.txt now compiles into decl %edi cmpl $3, %edi sbbl %eax, %eax andl $1, %eax ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124724 91177308-0d34-0410-b5e6-96231b3b80d8
* add a note, progress unblocked by PR8575 being fixed.Chris Lattner2011-01-311-0/+48
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* Teach DAGCombine to fold fold (sra (trunc (sr x, c1)), c2) -> (trunc (sra x, ↵Benjamin Kramer2011-01-301-21/+0
| | | | | | | | | | | | | | | | | | | c1+c2) when c1 equals the amount of bits that are truncated off. This happens all the time when a smul is promoted to a larger type. On x86-64 we now compile "int test(int x) { return x/10; }" into movslq %edi, %rax imulq $1717986919, %rax, %rax movq %rax, %rcx shrq $63, %rcx sarq $34, %rax <- used to be "shrq $32, %rax; sarl $2, %eax" addl %ecx, %eax This fires 96 times in gcc.c on x86-64. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124559 91177308-0d34-0410-b5e6-96231b3b80d8
* this isn't a memset, we do convert dest[i] to one though :)Chris Lattner2011-01-241-8/+0
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* with recent work, we now optimize this into:Chris Lattner2011-01-241-20/+0
| | | | | | | | | | | | | define i32 @foo(i32 %x) nounwind readnone ssp { entry: %tobool = icmp eq i32 %x, 0 %tmp5 = select i1 %tobool, i32 2, i32 1 ret i32 %tmp5 } git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124091 91177308-0d34-0410-b5e6-96231b3b80d8
* Add a memset loop that LoopIdiomRecognize doesn't recognize.Anders Carlsson2011-01-231-0/+8
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* add a noteChris Lattner2011-01-181-0/+20
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* Update README.txt to remove the DAE enhancement.Anders Carlsson2011-01-161-23/+0
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* add some commentaryChris Lattner2011-01-161-1/+14
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* Simplify a README.txt entry significantly to expose the core issue.Chandler Carruth2011-01-161-28/+26
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* typoChris Lattner2011-01-131-1/+1
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* memcpy + metadata = bliss :)Chris Lattner2011-01-131-0/+48
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* Teach constant folding to perform conversions from constant floatingChandler Carruth2011-01-111-55/+0
| | | | | | | | point values to their integer representation through the SSE intrinsic calls. This is the last part of a README.txt entry for which I have real world examples. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123206 91177308-0d34-0410-b5e6-96231b3b80d8
* Fix a random missed optimization by making InstCombine more aggressive when ↵Owen Anderson2011-01-111-15/+0
| | | | | | | | | determining which bits are demanded by a comparison against a constant. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123203 91177308-0d34-0410-b5e6-96231b3b80d8
* +0.0 vs -0.0 differences can be handled by looking at the user of theChris Lattner2011-01-101-3/+19
| | | | | | | | operation in some cases. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123190 91177308-0d34-0410-b5e6-96231b3b80d8
* expand on a noteChris Lattner2011-01-101-4/+9
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* typoChris Lattner2011-01-091-1/+1
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* xref a PR #Chris Lattner2011-01-091-22/+2
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* Add a note about the inability to model FP -> int conversions whichChandler Carruth2011-01-091-0/+55
| | | | | | | | perform rounding other than truncation in the IR. Common C code for this turns into really an LLVM intrinsic call that blocks a lot of further optimizations. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123135 91177308-0d34-0410-b5e6-96231b3b80d8
* Add a note about a missed FP optimization.Chandler Carruth2011-01-091-0/+24
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* Another missed memset in std::vector initialization.Chandler Carruth2011-01-091-0/+19
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* Fix a cut-paste-o so that the sample code is correct for my last note.Chandler Carruth2011-01-091-2/+6
| | | | | | | Also, switch to a more clear 'sink' function with its declaration to avoid any confusion about 'g'. Thanks for the suggestion Frits. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123113 91177308-0d34-0410-b5e6-96231b3b80d8
* Another missed optimization of trivial vector code.Chandler Carruth2011-01-091-0/+33
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* Add a note about vector's size-constructor producing dead stores.Chandler Carruth2011-01-091-0/+55
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* Add a note about a missed memset optimization from std::fill.Chandler Carruth2011-01-091-0/+30
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* Revert 122959, it needs more thought. Add it back to README.txt with ↵Benjamin Kramer2011-01-071-0/+22
| | | | | | additional notes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123030 91177308-0d34-0410-b5e6-96231b3b80d8
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