const Value* SV,
MachineBasicBlock *Default,
MachineBasicBlock *SwitchBB) {
- Case& BackCase = *(CR.Range.second-1);
-
// Size is the number of Cases represented by this range.
size_t Size = CR.Range.second - CR.Range.first;
if (Size > 3)
}
}
+ // Order cases by weight so the most likely case will be checked first.
+ BranchProbabilityInfo *BPI = FuncInfo.BPI;
+ if (BPI) {
+ for (CaseItr I = CR.Range.first, IE = CR.Range.second; I != IE; ++I) {
+ uint32_t IWeight = BPI->getEdgeWeight(SwitchBB->getBasicBlock(),
+ I->BB->getBasicBlock());
+ for (CaseItr J = CR.Range.first; J < I; ++J) {
+ uint32_t JWeight = BPI->getEdgeWeight(SwitchBB->getBasicBlock(),
+ J->BB->getBasicBlock());
+ if (IWeight > JWeight)
+ std::swap(*I, *J);
+ }
+ }
+ }
+
// Rearrange the case blocks so that the last one falls through if possible.
+ Case &BackCase = *(CR.Range.second-1);
if (NextBlock && Default != NextBlock && BackCase.BB != NextBlock) {
// The last case block won't fall through into 'NextBlock' if we emit the
// branches in this order. See if rearranging a case value would help.
- for (CaseItr I = CR.Range.first, E = CR.Range.second-1; I != E; ++I) {
+ // We start at the bottom as it's the case with the least weight.
+ for (CaseItr I = CR.Range.second-2, E = CR.Range.first-1; I != E; --I) {
if (I->BB == NextBlock) {
std::swap(*I, BackCase);
break;
--- /dev/null
+; RUN: llc -mtriple=x86_64-apple-darwin11 < %s | FileCheck %s
+
+; Check that the cases which lead to unreachable are checked after "10"
+
+define void @test1(i32 %x) nounwind uwtable ssp {
+entry:
+ switch i32 %x, label %if.end7 [
+ i32 0, label %if.then
+ i32 10, label %if.then2
+ i32 20, label %if.then5
+ ]
+
+; CHECK: test1:
+; CHECK-NOT: unr
+; CHECK: cmpl $10
+; CHECK: bar
+; CHECK: cmpl $20
+
+if.then:
+ tail call void @unr(i32 23) noreturn nounwind
+ unreachable
+
+if.then2:
+ tail call void @bar(i32 42) nounwind
+ br label %if.end7
+
+if.then5:
+ tail call void @unr(i32 5) noreturn nounwind
+ unreachable
+
+if.end7:
+ ret void
+}
+
+declare void @unr(i32) noreturn
+
+declare void @bar(i32)