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Ignore dbg intrinsics while folding switch instruction.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63802 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel 2009-02-05 00:30:42 +00:00
parent 4be0bdf7c1
commit 2cc86a1de1
2 changed files with 77 additions and 8 deletions
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27
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -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;

58
test/Transforms/SimplifyCFG/2003-08-17-FoldSwitch-dbg.ll Normal file
View File

@ -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
}