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path: root/lib/Transforms/Utils/SimplifyCFG.cpp
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2004-02-28Implement switch->br and br->switch folding by ripping out the switch->switchChris Lattner
and br->br code and generalizing it. This allows us to compile code like this: int test(Instruction *I) { if (isa<CastInst>(I)) return foo(7); else if (isa<BranchInst>(I)) return foo(123); else if (isa<UnwindInst>(I)) return foo(1241); else if (isa<SetCondInst>(I)) return foo(1); else if (isa<VAArgInst>(I)) return foo(42); return foo(-1); } into: int %_Z4testPN4llvm11InstructionE("struct.llvm::Instruction"* %I) { entry: %tmp.1.i.i.i.i.i.i.i = getelementptr "struct.llvm::Instruction"* %I, long 0, ubyte 4 ; <uint*> [#uses=1] %tmp.2.i.i.i.i.i.i.i = load uint* %tmp.1.i.i.i.i.i.i.i ; <uint> [#uses=2] %tmp.2.i.i.i.i.i.i = seteq uint %tmp.2.i.i.i.i.i.i.i, 27 ; <bool> [#uses=0] switch uint %tmp.2.i.i.i.i.i.i.i, label %endif.0 [ uint 27, label %then.0 uint 2, label %then.1 uint 5, label %then.2 uint 14, label %then.3 uint 15, label %then.3 uint 16, label %then.3 uint 17, label %then.3 uint 18, label %then.3 uint 19, label %then.3 uint 32, label %then.4 ] ... As well as handling the cases in 176.gcc and many other programs more effectively. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11964 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-26turn things like:Chris Lattner
if (X == 0 || X == 2) ...where the comparisons and branches are in different blocks... into a switch instruction. This comes up a lot in various programs, and works well with the switch/switch merging code I checked earlier. For example, this testcase: int switchtest(int C) { return C == 0 ? f(123) : C == 1 ? f(3123) : C == 4 ? f(312) : C == 5 ? f(1234): f(444); } is converted into this: switch int %C, label %cond_false.3 [ int 0, label %cond_true.0 int 1, label %cond_true.1 int 4, label %cond_true.2 int 5, label %cond_true.3 ] instead of a whole bunch of conditional branches. Admittedly the code is ugly, and incomplete. To be complete, we need to add br -> switch merging and switch -> br merging. For example, this testcase: struct foo { int Q, R, Z; }; #define A (X->Q+X->R * 123) int test(struct foo *X) { return A == 123 ? X1() : A == 12321 ? X2(): (A == 111 || A == 222) ? X3() : A == 875 ? X4() : X5(); } Gets compiled to this: switch int %tmp.7, label %cond_false.2 [ int 123, label %cond_true.0 int 12321, label %cond_true.1 int 111, label %cond_true.2 int 222, label %cond_true.2 ] ... cond_false.2: ; preds = %entry %tmp.52 = seteq int %tmp.7, 875 ; <bool> [#uses=1] br bool %tmp.52, label %cond_true.3, label %cond_false.3 where the branch could be folded into the switch. This kind of thing occurs *ALL OF THE TIME*, especially in programs like 176.gcc, which is a horrible mess of code. It contains stuff like *shudder*: #define SWITCH_TAKES_ARG(CHAR) \ ( (CHAR) == 'D' \ || (CHAR) == 'U' \ || (CHAR) == 'o' \ || (CHAR) == 'e' \ || (CHAR) == 'u' \ || (CHAR) == 'I' \ || (CHAR) == 'm' \ || (CHAR) == 'L' \ || (CHAR) == 'A' \ || (CHAR) == 'h' \ || (CHAR) == 'z') and #define CONST_OK_FOR_LETTER_P(VALUE, C) \ ((C) == 'I' ? SMALL_INTVAL (VALUE) \ : (C) == 'J' ? SMALL_INTVAL (-(VALUE)) \ : (C) == 'K' ? (unsigned)(VALUE) < 32 \ : (C) == 'L' ? ((VALUE) & 0xffff) == 0 \ : (C) == 'M' ? integer_ok_for_set (VALUE) \ : (C) == 'N' ? (VALUE) < 0 \ : (C) == 'O' ? (VALUE) == 0 \ : (C) == 'P' ? (VALUE) >= 0 \ : 0) and #define LEGITIMIZE_ADDRESS(X,OLDX,MODE,WIN) \ { \ if (GET_CODE (X) == PLUS && CONSTANT_ADDRESS_P (XEXP (X, 1))) \ (X) = gen_rtx (PLUS, SImode, XEXP (X, 0), \ copy_to_mode_reg (SImode, XEXP (X, 1))); \ if (GET_CODE (X) == PLUS && CONSTANT_ADDRESS_P (XEXP (X, 0))) \ (X) = gen_rtx (PLUS, SImode, XEXP (X, 1), \ copy_to_mode_reg (SImode, XEXP (X, 0))); \ if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 0)) == MULT) \ (X) = gen_rtx (PLUS, SImode, XEXP (X, 1), \ force_operand (XEXP (X, 0), 0)); \ if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == MULT) \ (X) = gen_rtx (PLUS, SImode, XEXP (X, 0), \ force_operand (XEXP (X, 1), 0)); \ if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 0)) == PLUS) \ (X) = gen_rtx (PLUS, Pmode, force_operand (XEXP (X, 0), NULL_RTX),\ XEXP (X, 1)); \ if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == PLUS) \ (X) = gen_rtx (PLUS, Pmode, XEXP (X, 0), \ force_operand (XEXP (X, 1), NULL_RTX)); \ if (GET_CODE (X) == SYMBOL_REF || GET_CODE (X) == CONST \ || GET_CODE (X) == LABEL_REF) \ (X) = legitimize_address (flag_pic, X, 0, 0); \ if (memory_address_p (MODE, X)) \ goto WIN; } and others. These macros get used multiple times of course. These are such lovely candidates for macros, aren't they? :) This code also nicely handles LLVM constructs that look like this: if (isa<CastInst>(I)) ... else if (isa<BranchInst>(I)) ... else if (isa<SetCondInst>(I)) ... else if (isa<UnwindInst>(I)) ... else if (isa<VAArgInst>(I)) ... where the isa can obviously be a dyn_cast as well. Switch instructions are a good thing. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11870 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-24If a block is made dead, make sure to promptly remove it.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11799 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-24Implement SimplifyCFG/switch_switch_fold.llChris Lattner
This case occurs many times in various benchmarks, especially when combined with the previous patch. This allows it to get stuff like: if (X == 4 || X == 3) if (X == 5 || X == 8) and switch (X) { case 4: case 5: case 6: if (X == 4 || X == 5) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11797 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-24Rearrange code a bitChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11793 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-24Implement: test/Regression/Transforms/SimplifyCFG/switch_create.llChris Lattner
This turns code like this: if (X == 4 | X == 7) and if (X != 4 & X != 7) into switch instructions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11792 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-16Implement test/Regression/Transforms/SimplifyCFG/UncondBranchToReturn.ll,Chris Lattner
see the testcase for the reasoning. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11496 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-11Implement SimplifyCFG/PhiEliminate.llChris Lattner
Having a proper 'select' instruction would allow the elimination of a lot of the special case cruft in this patch, but we don't have one yet. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11307 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-11The hasConstantReferences predicate always returns false.Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11301 91177308-0d34-0410-b5e6-96231b3b80d8
2004-02-08rename the "exceptional" destination of an invoke instruction to the ↵Chris Lattner
'unwind' dest git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11202 91177308-0d34-0410-b5e6-96231b3b80d8
2004-01-09Finegrainify namespacificationChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10727 91177308-0d34-0410-b5e6-96231b3b80d8
2003-11-11Put all LLVM code into the llvm namespace, as per bug 109.Brian Gaeke
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9903 91177308-0d34-0410-b5e6-96231b3b80d8
2003-10-20Added LLVM project notice to the top of every C++ source file.John Criswell
Header files will be on the way. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9298 91177308-0d34-0410-b5e6-96231b3b80d8
2003-10-10Fix spelling.Misha Brukman
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9027 91177308-0d34-0410-b5e6-96231b3b80d8
2003-09-08Eliminate support for the llvm.unwind intrinisic, using the Unwind ↵Chris Lattner
instruction instead git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8411 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-24Implement SimplifyCFG/InvokeEliminate.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8126 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-17Fix bug: SimplifyCFG/2003-08-17-BranchFoldOrdering.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7921 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-05Fix bug: SimplifyCFG/2003-08-05-InvokeCrash.llChris Lattner
Fix bug: SimplifyCFG/2003-08-05-MishandleInvoke.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7599 91177308-0d34-0410-b5e6-96231b3b80d8
2003-04-23Remove unnecesary &*'sChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5872 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-07Fix bug: SimplifyCFG/2003-03-07-DominateProblem.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5722 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-05Implement CFGSimplify/PhiBlockMerge*.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5702 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-05Implement testcase CFGSimplify/EqualPHIEdgeBlockMerge.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5699 91177308-0d34-0410-b5e6-96231b3b80d8
2002-10-29Fix spelling of `propagate'.Misha Brukman
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4423 91177308-0d34-0410-b5e6-96231b3b80d8
2002-10-08Changes to support PHINode::removeIncoming changesChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4079 91177308-0d34-0410-b5e6-96231b3b80d8
2002-09-24Fix bug: SimplifyCFG/2002-09-24-PHIAssertion.llChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3913 91177308-0d34-0410-b5e6-96231b3b80d8
2002-09-24Minor cleanupsChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3904 91177308-0d34-0410-b5e6-96231b3b80d8
2002-07-29Allow folding of basic blocks that have PHI nodes in them, fixing "bug":Chris Lattner
test/Regression/Transforms/SimplifyCFG/2002-06-24-PHINode.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3128 91177308-0d34-0410-b5e6-96231b3b80d8
2002-06-25*** empty log message ***Chris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2777 91177308-0d34-0410-b5e6-96231b3b80d8
2002-05-21Add implementation of SimplifyCFGChris Lattner
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2701 91177308-0d34-0410-b5e6-96231b3b80d8
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