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[mips] Fix compact branch hazard detection, part 2

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Follow up to D27209 fix, this patch now properly handles single transient
instruction in basic block.

Patch by Aleksandar Beserminji.

Differential Revision: https://reviews.llvm.org/D27856

llvm-svn: 290361
This commit is contained in:
Petar Jovanovic
2016-12-22 19:29:50 +00:00
parent 8839124848
commit 8a4e63994e
2 changed files with 49 additions and 22 deletions
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37
llvm/lib/Target/Mips/MipsHazardSchedule.cpp
View File

@@ -103,24 +103,23 @@ static Iter getNextMachineInstrInBB(Iter Position) {
// Find the next real instruction from the current position, looking through
// basic block boundaries.
static Iter getNextMachineInstr(Iter Position) {
if (std::next(Position) == Position->getParent()->end()) {
const MachineBasicBlock * MBB = (&*Position)->getParent();
for (auto *Succ : MBB->successors()) {
if (MBB->isLayoutSuccessor(Succ)) {
Iter I = Succ->begin();
Iter Next = getNextMachineInstrInBB(I);
if (Next == Succ->end()) {
return getNextMachineInstr(I);
} else {
return I;
}
}
static Iter getNextMachineInstr(Iter Position, MachineBasicBlock *Parent) {
if (Position == Parent->end()) {
MachineBasicBlock *Succ = Parent->getNextNode();
if (Succ != nullptr && Parent->isSuccessor(Succ)) {
Position = Succ->begin();
Parent = Succ;
} else {
llvm_unreachable(
"Should have identified the end of the function earlier!");
}
llvm_unreachable("Should have identified the end of the function earlier!");
}
return getNextMachineInstrInBB(Position);
Iter Instr = getNextMachineInstrInBB(Position);
if (Instr == Parent->end()) {
return getNextMachineInstr(Instr, Parent);
}
return Instr;
}
bool MipsHazardSchedule::runOnMachineFunction(MachineFunction &MF) {
@@ -146,13 +145,7 @@ bool MipsHazardSchedule::runOnMachineFunction(MachineFunction &MF) {
bool LastInstInFunction =
std::next(I) == FI->end() && std::next(FI) == MF.end();
if (!LastInstInFunction) {
if (std::next(I) != FI->end()) {
// Start looking from the next instruction in the basic block.
Inst = getNextMachineInstr(std::next(I));
} else {
// Next instruction in the physical successor basic block.
Inst = getNextMachineInstr(I);
}
Inst = getNextMachineInstr(std::next(I), &*FI);
}
if (LastInstInFunction || !TII->SafeInForbiddenSlot(*Inst)) {

34
llvm/test/CodeGen/Mips/compactbranches/unsafe-in-forbidden-slot.ll Normal file
View File

@@ -0,0 +1,34 @@
; RUN: llc -march=mips64el -O0 -mcpu=mips64r6 < %s | FileCheck %s
; RUN: llc -march=mips64 -O0 -mcpu=mips64r6 < %s | FileCheck %s
@boo = global i32 0, align 4
; Function Attrs: nounwind
define void @_Z3foov() #0 {
entry:
%0 = load volatile i32, i32* @boo, align 4
switch i32 %0, label %sw.epilog [
i32 0, label %sw.bb
i32 1, label %sw.bb1
i32 2, label %sw.bb1
]
sw.bb: ; preds = %entry
store volatile i32 1, i32* @boo, align 4
br label %sw.epilog
; CHECK: beqzc
; CHECK-NEXT: nop
; CHECK-NEXT: .LBB
; CHECK-NEXT: j
sw.bb1: ; preds = %entry, %entry
store volatile i32 2, i32* @boo, align 4
br label %sw.epilog
; CHECK: bnezc
; CHECK-NEXT: nop
; CHECK-NEXT: .LBB
; CHECK-NEXT: j
sw.epilog: ; preds = %entry, %sw.bb1, %sw.bb
ret void
}