diff options
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 27 | ||||
| -rw-r--r-- | test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll | 58 |
2 files changed, 77 insertions, 8 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index ba00f61..d9c4b69 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -1330,6 +1330,20 @@ static bool FoldTwoEntryPHINode(PHINode *PN) { return true; } +/// isTerminatorFirstRelevantInsn - Return true if Term is very first +/// instruction ignoring Phi nodes and dbg intrinsics. +static bool isTerminatorFirstRelevantInsn(BasicBlock *BB, Instruction *Term) { + BasicBlock::iterator BBI = Term; + while (BBI != BB->begin()) { + --BBI; + if (!isa<DbgInfoIntrinsic>(BBI)) + break; + } + if (isa<PHINode>(BBI) || &*BBI == Term) + return true; + return false; +} + /// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes /// to two returning blocks, try to merge them together into one return, /// introducing a select if the return values disagree. @@ -1343,12 +1357,10 @@ static bool SimplifyCondBranchToTwoReturns(BranchInst *BI) { // Check to ensure both blocks are empty (just a return) or optionally empty // with PHI nodes. If there are other instructions, merging would cause extra // computation on one path or the other. - BasicBlock::iterator BBI = TrueRet; - if (BBI != TrueSucc->begin() && !isa<PHINode>(--BBI)) - return false; // Not empty with optional phi nodes. - BBI = FalseRet; - if (BBI != FalseSucc->begin() && !isa<PHINode>(--BBI)) - return false; // Not empty with optional phi nodes. + if (!isTerminatorFirstRelevantInsn(TrueSucc, TrueRet)) + return false; + if (!isTerminatorFirstRelevantInsn(FalseSucc, FalseRet)) + return false; // Okay, we found a branch that is going to two return nodes. If // there is no return value for this function, just change the @@ -1750,8 +1762,7 @@ bool llvm::SimplifyCFG(BasicBlock *BB) { // different return values, fold the replace the branch/return with a select // and return. if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { - BasicBlock::iterator BBI = BB->getTerminator(); - if (BBI == BB->begin() || isa<PHINode>(--BBI)) { + if (isTerminatorFirstRelevantInsn(BB, BB->getTerminator())) { // Find predecessors that end with branches. SmallVector<BasicBlock*, 8> UncondBranchPreds; SmallVector<BranchInst*, 8> CondBranchPreds; diff --git a/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll b/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll new file mode 100644 index 0000000..c9f5090 --- /dev/null +++ b/test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll @@ -0,0 +1,58 @@ +; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | \ +; RUN: not grep switch + + + %llvm.dbg.anchor.type = type { i32, i32 } + %llvm.dbg.compile_unit.type = type { i32, { }*, i32, i8*, i8*, i8*, i1, i1, i8* } + +@llvm.dbg.compile_units = linkonce constant %llvm.dbg.anchor.type { i32 458752, i32 17 }, section "llvm.metadata" ; + +@.str = internal constant [4 x i8] c"a.c\00", section "llvm.metadata" ; <[4 x i8]*> [#uses=1] +@.str1 = internal constant [6 x i8] c"/tmp/\00", section "llvm.metadata" ; <[6 x i8]*> [#uses=1] +@.str2 = internal constant [55 x i8] c"4.2.1 (Based on Apple Inc. build 5636) (LLVM build 00)\00", section "llvm.metadata" ; <[55 x i8]*> [#uses=1] +@llvm.dbg.compile_unit = internal constant %llvm.dbg.compile_unit.type { i32 458769, { }* bitcast (%llvm.dbg.anchor.type* @llvm.dbg.compile_units to { }*), i32 1, i8* getelementptr ([4 x i8]* @.str, i32 0, i32 0), i8* getelementptr ([6 x i8]* @.str1, i32 0, i32 0), i8* getelementptr ([55 x i8]* @.str2, i32 0, i32 0), i1 true, i1 false, i8* null }, section "llvm.metadata" ; <%llvm.dbg.compile_unit.type*> [#uses=1] + +declare void @llvm.dbg.stoppoint(i32, i32, { }*) nounwind + +; Test folding all to same dest +define i32 @test3(i1 %C) { + br i1 %C, label %Start, label %TheDest +Start: ; preds = %0 +call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*)) + switch i32 3, label %TheDest [ + i32 0, label %TheDest + i32 1, label %TheDest + i32 2, label %TheDest + i32 5, label %TheDest + ] +TheDest: ; preds = %Start, %Start, %Start, %Start, %Start, %0 + ret i32 1234 +} + +; Test folding switch -> branch +define i32 @test4(i32 %C) { + switch i32 %C, label %L1 [ + i32 0, label %L2 + ] +L1: ; preds = %0 +call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*)) + ret i32 0 +L2: ; preds = %0 +call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*)) + ret i32 1 +} + +; Can fold into a cond branch! +define i32 @test5(i32 %C) { + switch i32 %C, label %L1 [ + i32 0, label %L2 + i32 123, label %L1 + ] +L1: ; preds = %0, %0 +call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*)) + ret i32 0 +L2: ; preds = %0 +call void @llvm.dbg.stoppoint(i32 5, i32 0, { }* bitcast (%llvm.dbg.compile_unit.type* @llvm.dbg.compile_unit to { }*)) + ret i32 1 +} + |