[x86] Fix another trivial bug in x86 flags copy lowering that has been
there for a long time. The boolean tracking whether we saw a kill of the flags was supposed to be per-block we are scanning and instead was outside that loop and never cleared. It requires a quite contrived test case to hit this as you have to have multiple levels of successors and interleave them with kills. I've included such a test case here. This is another bug found testing SLH and extracted to its own focused patch. llvm-svn: 336876
This commit is contained in:
Chandler Carruth
parent
be996bd2d9
commit
b4faf4ce08
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@ -413,9 +413,9 @@ bool X86FlagsCopyLoweringPass::runOnMachineFunction(MachineFunction &MF) {
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LLVM_DEBUG(dbgs() << "Rewriting copy: "; CopyI->dump());
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// Scan for usage of newly set EFLAGS so we can rewrite them. We just buffer
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// jumps because their usage is very constrained.
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bool FlagsKilled = false;
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// While rewriting uses, we buffer jumps and rewrite them in a second pass
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// because doing so will perturb the CFG that we are walking to find the
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// uses in the first place.
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SmallVector<MachineInstr *, 4> JmpIs;
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// Gather the condition flags that have already been preserved in
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@ -436,6 +436,9 @@ bool X86FlagsCopyLoweringPass::runOnMachineFunction(MachineFunction &MF) {
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do {
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MachineBasicBlock &UseMBB = *Blocks.pop_back_val();
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// Track when if/when we find a kill of the flags in this block.
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bool FlagsKilled = false;
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// We currently don't do any PHI insertion and so we require that the
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// test basic block dominates all of the use basic blocks.
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//
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@ -78,6 +78,12 @@
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call void @foo()
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ret i64 0
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}
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define i64 @test_branch_with_interleaved_livein_and_kill(i64 %a, i64 %b) {
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entry:
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call void @foo()
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ret i64 0
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}
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...
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---
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name: test_branch
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@ -632,3 +638,103 @@ body: |
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RET 0, $rax
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...
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---
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name: test_branch_with_interleaved_livein_and_kill
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# CHECK-LABEL: name: test_branch_with_interleaved_livein_and_kill
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liveins:
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- { reg: '$rdi', virtual-reg: '%0' }
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- { reg: '$rsi', virtual-reg: '%1' }
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body: |
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bb.0:
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successors: %bb.1, %bb.2, %bb.5
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liveins: $rdi, $rsi
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%0:gr64 = COPY $rdi
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%1:gr64 = COPY $rsi
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CMP64rr %0, %1, implicit-def $eflags
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%2:gr64 = COPY $eflags
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; CHECK-NOT: COPY{{( killed)?}} $eflags
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; CHECK: %[[S_REG:[^:]*]]:gr8 = SETSr implicit $eflags
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; CHECK-NEXT: %[[P_REG:[^:]*]]:gr8 = SETPr implicit $eflags
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; CHECK-NEXT: %[[NE_REG:[^:]*]]:gr8 = SETNEr implicit $eflags
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; CHECK-NEXT: %[[A_REG:[^:]*]]:gr8 = SETAr implicit $eflags
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; CHECK-NEXT: %[[B_REG:[^:]*]]:gr8 = SETBr implicit $eflags
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; CHECK-NEXT: %[[O_REG:[^:]*]]:gr8 = SETOr implicit $eflags
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; CHECK-NOT: COPY{{( killed)?}} $eflags
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ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
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CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
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ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
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$eflags = COPY %2
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JA_1 %bb.1, implicit $eflags
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JB_1 %bb.2, implicit $eflags
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JMP_1 %bb.5
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; CHECK-NOT: $eflags =
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;
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; CHECK: TEST8rr %[[A_REG]], %[[A_REG]], implicit-def $eflags
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; CHECK-NEXT: JNE_1 %bb.1, implicit killed $eflags
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; CHECK-SAME: {{$[[:space:]]}}
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; CHECK-NEXT: bb.6:
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; CHECK-NEXT: successors: {{.*$}}
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; CHECK-SAME: {{$[[:space:]]}}
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; CHECK-NEXT: TEST8rr %[[B_REG]], %[[B_REG]], implicit-def $eflags
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; CHECK-NEXT: JNE_1 %bb.2, implicit killed $eflags
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; CHECK-NEXT: JMP_1 %bb.5
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bb.1:
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liveins: $eflags
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%3:gr64 = CMOVE64rr %0, %1, implicit killed $eflags
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; CHECK-NOT: $eflags =
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; CHECK: TEST8rr %[[NE_REG]], %[[NE_REG]], implicit-def $eflags
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; CHECK-NEXT: %3:gr64 = CMOVE64rr %0, %1, implicit killed $eflags
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$rax = COPY %3
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RET 0, $rax
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bb.2:
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; The goal is to have another batch of successors discovered in a block
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; between two successors which kill $eflags. This ensures that neither of
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; the surrounding kills impact recursing through this block.
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successors: %bb.3, %bb.4
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liveins: $eflags
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JO_1 %bb.3, implicit $eflags
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JMP_1 %bb.4
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; CHECK-NOT: $eflags =
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;
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; CHECK: TEST8rr %[[O_REG]], %[[O_REG]], implicit-def $eflags
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; CHECK-NEXT: JNE_1 %bb.3, implicit killed $eflags
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; CHECK-NEXT: JMP_1 %bb.4
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bb.3:
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liveins: $eflags
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%4:gr64 = CMOVNE64rr %0, %1, implicit $eflags
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; CHECK-NOT: $eflags =
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; CHECK: TEST8rr %[[NE_REG]], %[[NE_REG]], implicit-def $eflags
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; CHECK-NEXT: %4:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
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$rax = COPY %4
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RET 0, $rax
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bb.4:
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liveins: $eflags
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%5:gr64 = CMOVP64rr %0, %1, implicit $eflags
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; CHECK-NOT: $eflags =
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; CHECK: TEST8rr %[[P_REG]], %[[P_REG]], implicit-def $eflags
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; CHECK-NEXT: %5:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
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$rax = COPY %5
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RET 0, $rax
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bb.5:
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liveins: $eflags
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%6:gr64 = CMOVS64rr %0, %1, implicit killed $eflags
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; CHECK-NOT: $eflags =
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; CHECK: TEST8rr %[[S_REG]], %[[S_REG]], implicit-def $eflags
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; CHECK-NEXT: %6:gr64 = CMOVNE64rr %0, %1, implicit killed $eflags
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$rax = COPY %6
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RET 0, $rax
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...
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