forked from OSchip/llvm-project
Re-apply 101075 and fix it properly. Just reuse the debug info of the branch instruction being optimized. There is no need to --I which can deref off start of the BB.
llvm-svn: 101162
This commit is contained in:
Evan Cheng
parent
5e575c03b8
commit
4ca4bc6f95
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@ -1684,6 +1684,7 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
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// Start from the bottom of the block and work up, examining the
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// terminator instructions.
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MachineBasicBlock::iterator I = MBB.end();
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MachineBasicBlock::iterator UnCondBrIter = MBB.end();
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while (I != MBB.begin()) {
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--I;
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if (I->isDebugValue())
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@ -1701,6 +1702,8 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
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// Handle unconditional branches.
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if (I->getOpcode() == X86::JMP_4) {
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UnCondBrIter = I;
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if (!AllowModify) {
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TBB = I->getOperand(0).getMBB();
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continue;
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@ -1718,10 +1721,11 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
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TBB = 0;
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I->eraseFromParent();
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I = MBB.end();
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UnCondBrIter = MBB.end();
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continue;
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}
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// TBB is used to indicate the unconditinal destination.
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// TBB is used to indicate the unconditional destination.
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TBB = I->getOperand(0).getMBB();
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continue;
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}
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@ -1733,6 +1737,45 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
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// Working from the bottom, handle the first conditional branch.
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if (Cond.empty()) {
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MachineBasicBlock *TargetBB = I->getOperand(0).getMBB();
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if (AllowModify && UnCondBrIter != MBB.end() &&
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MBB.isLayoutSuccessor(TargetBB)) {
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// If we can modify the code and it ends in something like:
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//
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// jCC L1
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// jmp L2
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// L1:
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// ...
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// L2:
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//
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// Then we can change this to:
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//
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// jnCC L2
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// L1:
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// ...
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// L2:
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//
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// Which is a bit more efficient.
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// We conditionally jump to the fall-through block.
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BranchCode = GetOppositeBranchCondition(BranchCode);
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unsigned JNCC = GetCondBranchFromCond(BranchCode);
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MachineBasicBlock::iterator OldInst = I;
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BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(JNCC))
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.addMBB(UnCondBrIter->getOperand(0).getMBB());
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BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(X86::JMP_4))
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.addMBB(TargetBB);
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MBB.addSuccessor(TargetBB);
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OldInst->eraseFromParent();
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UnCondBrIter->eraseFromParent();
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// Restart the analysis.
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UnCondBrIter = MBB.end();
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I = MBB.end();
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continue;
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}
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FBB = TBB;
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TBB = I->getOperand(0).getMBB();
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Cond.push_back(MachineOperand::CreateImm(BranchCode));
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@ -0,0 +1,42 @@
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; RUN: llc < %s -mtriple=i386-apple-darwin -mcpu=core2
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; rdar://7857830
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%0 = type opaque
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%1 = type opaque
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define void @t(%0* %self, i8* nocapture %_cmd, %1* %scroller, i32 %hitPart, float %multiplier) nounwind optsize ssp {
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entry:
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switch i32 %hitPart, label %if.else [
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i32 7, label %if.then
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i32 8, label %if.then
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]
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if.then: ; preds = %entry, %entry
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%tmp69 = load float* null, align 4 ; <float> [#uses=1]
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%cmp19 = icmp eq %1* null, %scroller ; <i1> [#uses=2]
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%cond = select i1 %cmp19, float %tmp69, float 0.000000e+00 ; <float> [#uses=1]
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%call36 = call i64 bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to i64 (i8*, i8*)*)(i8* undef, i8* undef) nounwind optsize ; <i64> [#uses=2]
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br i1 %cmp19, label %cond.true32, label %cond.false39
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cond.true32: ; preds = %if.then
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%sroa.store.elt68 = lshr i64 %call36, 32 ; <i64> [#uses=1]
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%0 = trunc i64 %sroa.store.elt68 to i32 ; <i32> [#uses=1]
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br label %cond.end47
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cond.false39: ; preds = %if.then
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%1 = trunc i64 %call36 to i32 ; <i32> [#uses=1]
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br label %cond.end47
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cond.end47: ; preds = %cond.false39, %cond.true32
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%cond48.in = phi i32 [ %0, %cond.true32 ], [ %1, %cond.false39 ] ; <i32> [#uses=1]
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%cond48 = bitcast i32 %cond48.in to float ; <float> [#uses=1]
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%div = fdiv float %cond, undef ; <float> [#uses=1]
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%div58 = fdiv float %div, %cond48 ; <float> [#uses=1]
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call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*, float)*)(i8* undef, i8* undef, float %div58) nounwind optsize
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ret void
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if.else: ; preds = %entry
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ret void
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}
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declare i8* @objc_msgSend(i8*, i8*, ...)
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@ -67,3 +67,42 @@ return: ; preds = %entry
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; CHECK-NEXT: orl 8(%esp), %eax
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; CHECK-NEXT: je LBB3_2
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}
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; <rdar://problem/7598384>:
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;
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; jCC L1
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; jmp L2
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; L1:
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; ...
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; L2:
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; ...
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;
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; to:
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;
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; jnCC L2
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; L1:
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; ...
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; L2:
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; ...
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define float @test4(float %x, float %y) nounwind readnone optsize ssp {
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entry:
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%0 = fpext float %x to double ; <double> [#uses=1]
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%1 = fpext float %y to double ; <double> [#uses=1]
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%2 = fmul double %0, %1 ; <double> [#uses=3]
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%3 = fcmp oeq double %2, 0.000000e+00 ; <i1> [#uses=1]
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br i1 %3, label %bb2, label %bb1
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; CHECK: jne
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; CHECK-NEXT: jnp
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; CHECK-NOT: jmp
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; CHECK: LBB
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bb1: ; preds = %entry
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%4 = fadd double %2, -1.000000e+00 ; <double> [#uses=1]
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br label %bb2
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bb2: ; preds = %entry, %bb1
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%.0.in = phi double [ %4, %bb1 ], [ %2, %entry ] ; <double> [#uses=1]
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%.0 = fptrunc double %.0.in to float ; <float> [#uses=1]
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ret float %.0
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}
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