From ae9753b29d63ee83a0bafe51d037b219b0f8ed7a Mon Sep 17 00:00:00 2001 From: Wojciech Matyjewicz Date: Sun, 15 Jun 2008 19:07:39 +0000 Subject: [PATCH] Fix PR2434. When scanning for exising binary operator to reuse don't take into account the instrucion pointed by InsertPt. Thanks to it, returning the new value of InsertPt to the InsertBinop() caller can be avoided. The bug was, actually, in visitAddRecExpr() method which wasn't correctly handling changes of InsertPt. There shouldn't be any performance regression, as -gvn pass (run after -indvars) removes any redundant binops. llvm-svn: 52291 --- .../llvm/Analysis/ScalarEvolutionExpander.h | 2 +- llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 30 +++++++++---------- .../2008-06-15-SCEVExpanderBug.ll | 17 +++++++++++ 3 files changed, 33 insertions(+), 16 deletions(-) create mode 100644 llvm/test/Transforms/IndVarsSimplify/2008-06-15-SCEVExpanderBug.ll diff --git a/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h b/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h index daff373348b8..9a69b2416516 100644 --- a/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h +++ b/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h @@ -88,7 +88,7 @@ namespace llvm { /// InsertBinop - Insert the specified binary operator, doing a small amount /// of work to avoid inserting an obviously redundant operation. static Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, - Value *RHS, Instruction *&InsertPt); + Value *RHS, Instruction *InsertPt); protected: Value *expand(SCEV *S); diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index a241960b374c..9872ced519ed 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -73,7 +73,7 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V, /// InsertBinop - Insert the specified binary operator, doing a small amount /// of work to avoid inserting an obviously redundant operation. Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, - Value *RHS, Instruction *&InsertPt) { + Value *RHS, Instruction *InsertPt) { // Fold a binop with constant operands. if (Constant *CLHS = dyn_cast(LHS)) if (Constant *CRHS = dyn_cast(RHS)) @@ -81,21 +81,21 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, // Do a quick scan to see if we have this binop nearby. If so, reuse it. unsigned ScanLimit = 6; - for (BasicBlock::iterator IP = InsertPt, E = InsertPt->getParent()->begin(); - ScanLimit; --IP, --ScanLimit) { - if (BinaryOperator *BinOp = dyn_cast(IP)) - if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS && - BinOp->getOperand(1) == RHS) { - // If we found the instruction *at* the insert point, insert later - // instructions after it. - if (BinOp == InsertPt) - InsertPt = ++IP; - return BinOp; - } - if (IP == E) break; + BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin(); + if (InsertPt != BlockBegin) { + // Scanning starts from the last instruction before InsertPt. + BasicBlock::iterator IP = InsertPt; + --IP; + for (; ScanLimit; --IP, --ScanLimit) { + if (BinaryOperator *BinOp = dyn_cast(IP)) + if (BinOp->getOpcode() == Opcode && BinOp->getOperand(0) == LHS && + BinOp->getOperand(1) == RHS) + return BinOp; + if (IP == BlockBegin) break; + } } - - // If we don't have + + // If we haven't found this binop, insert it. return BinaryOperator::Create(Opcode, LHS, RHS, "tmp", InsertPt); } diff --git a/llvm/test/Transforms/IndVarsSimplify/2008-06-15-SCEVExpanderBug.ll b/llvm/test/Transforms/IndVarsSimplify/2008-06-15-SCEVExpanderBug.ll new file mode 100644 index 000000000000..aac8d9789464 --- /dev/null +++ b/llvm/test/Transforms/IndVarsSimplify/2008-06-15-SCEVExpanderBug.ll @@ -0,0 +1,17 @@ +; RUN: llvm-as < %s | opt -indvars -disable-output +; PR2434 + +define fastcc void @regcppop() nounwind { +entry: + %tmp61 = add i32 0, -5 ; [#uses=1] + br label %bb + +bb: ; preds = %bb, %entry + %PL_savestack_ix.tmp.0 = phi i32 [ %tmp61, %entry ], [ %tmp127, %bb ] ; [#uses=2] + %indvar10 = phi i32 [ 0, %entry ], [ %indvar.next11, %bb ] ; [#uses=2] + %tmp13 = mul i32 %indvar10, -4 ; [#uses=0] + %tmp111 = add i32 %PL_savestack_ix.tmp.0, -3 ; [#uses=0] + %tmp127 = add i32 %PL_savestack_ix.tmp.0, -4 ; [#uses=1] + %indvar.next11 = add i32 %indvar10, 1 ; [#uses=1] + br label %bb +}