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StackColoring: better handling of statically unreachable code
Summary: Avoid assert/crash during liveness calculation in situations where the incoming machine function has statically unreachable BBs. Second attempt at submitting; this version of the change includes a revised testcase. Fixes PR37130. Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D47372 llvm-svn: 333416
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Than McIntosh
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@ -782,8 +782,11 @@ void StackColoring::calculateLocalLiveness() {
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for (MachineBasicBlock::const_pred_iterator PI = BB->pred_begin(),
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PE = BB->pred_end(); PI != PE; ++PI) {
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LivenessMap::const_iterator I = BlockLiveness.find(*PI);
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assert(I != BlockLiveness.end() && "Predecessor not found");
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LocalLiveIn |= I->second.LiveOut;
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// PR37130: transformations prior to stack coloring can
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// sometimes leave behind statically unreachable blocks; these
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// can be safely skipped here.
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if (I != BlockLiveness.end())
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LocalLiveIn |= I->second.LiveOut;
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}
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// Compute LiveOut by subtracting out lifetimes that end in this
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153
test/CodeGen/X86/PR37310.mir
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153
test/CodeGen/X86/PR37310.mir
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@ -0,0 +1,153 @@
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# RUN: llc -mtriple=x86_64-unknown-linux-gnu -mcpu=corei7 -start-before dwarfehprepare -no-stack-coloring=false -stop-after stack-coloring -o - %s
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# Test to insure that the liveness analysis in the StackColoring
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# pass gracefully handles statically unreachable blocks. See PR 37310.
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# This MIR testcase was created by compiling the following test, first
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# with "clang -emit-llvm -S" and then "llc -stop-before stack-coloring",
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# and finally editing the resulting MIR by hand to introduce a statically
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# unreachable BB (to wit: rename all bb.3 to bb.4, rename bb.2 to bb.3,
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# then add bb.2 with unconditional jump to bb.4).
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# Original C code:
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# extern int inita(int *);
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# void foo(int x) {
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# if (x != 3) {
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# int q[128];
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# inita(&q[0]);
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# return;
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# }
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# int r[128];
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# inita(&r[x]);
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# }
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--- |
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define void @foo(i32 %x) {
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entry:
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%q = alloca [128 x i32], align 16
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%r = alloca [128 x i32], align 16
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%cmp = icmp eq i32 %x, 3
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br i1 %cmp, label %if.end, label %if.then
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if.then: ; preds = %entry
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%0 = bitcast [128 x i32]* %q to i8*
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call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %0)
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%arrayidx2 = bitcast [128 x i32]* %q to i32*
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%call = call i32 @inita(i32* nonnull %arrayidx2)
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call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %0)
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br label %return
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unreachable:
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br label %return
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if.end: ; preds = %entry
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%1 = bitcast [128 x i32]* %r to i8*
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call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %1)
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%arrayidx1 = getelementptr inbounds [128 x i32], [128 x i32]* %r, i64 0, i64 3
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%call2 = call i32 @inita(i32* nonnull %arrayidx1)
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call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %1)
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br label %return
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return: ; preds = %if.end, %if.then
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ret void
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}
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declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
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declare i32 @inita(i32*)
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declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
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declare void @llvm.stackprotector(i8*, i8**)
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...
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---
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name: foo
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alignment: 4
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exposesReturnsTwice: false
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legalized: false
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regBankSelected: false
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selected: false
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failedISel: false
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tracksRegLiveness: true
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registers:
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- { id: 0, class: gr32, preferred-register: '' }
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- { id: 1, class: gr32, preferred-register: '' }
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- { id: 2, class: gr64, preferred-register: '' }
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- { id: 3, class: gr32, preferred-register: '' }
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- { id: 4, class: gr64, preferred-register: '' }
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- { id: 5, class: gr32, preferred-register: '' }
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liveins:
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- { reg: '$edi', virtual-reg: '%0' }
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frameInfo:
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isFrameAddressTaken: false
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isReturnAddressTaken: false
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hasStackMap: false
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hasPatchPoint: false
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stackSize: 0
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offsetAdjustment: 0
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maxAlignment: 16
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adjustsStack: false
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hasCalls: true
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stackProtector: ''
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maxCallFrameSize: 4294967295
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hasOpaqueSPAdjustment: false
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hasVAStart: false
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hasMustTailInVarArgFunc: false
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localFrameSize: 0
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savePoint: ''
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restorePoint: ''
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fixedStack:
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stack:
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- { id: 0, name: q, type: default, offset: 0, size: 512, alignment: 16,
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stack-id: 0, callee-saved-register: '', callee-saved-restored: true,
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debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
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- { id: 1, name: r, type: default, offset: 0, size: 512, alignment: 16,
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stack-id: 0, callee-saved-register: '', callee-saved-restored: true,
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debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
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constants:
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body: |
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bb.0.entry:
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successors: %bb.3(0x40000000), %bb.1(0x40000000)
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liveins: $edi
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%0:gr32 = COPY $edi
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%1:gr32 = SUB32ri8 %0, 3, implicit-def $eflags
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JE_1 %bb.3, implicit $eflags
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JMP_1 %bb.1
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bb.1.if.then:
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successors: %bb.4(0x80000000)
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LIFETIME_START %stack.0.q
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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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%2:gr64 = LEA64r %stack.0.q, 1, $noreg, 0, $noreg
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$rdi = COPY %2
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CALL64pcrel32 @inita, 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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%3:gr32 = COPY $eax
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LIFETIME_END %stack.0.q
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JMP_1 %bb.4
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bb.2.unreachable:
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successors: %bb.4(0x80000000)
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JMP_1 %bb.4
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bb.3.if.end:
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successors: %bb.4(0x80000000)
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LIFETIME_START %stack.1.r
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%4:gr64 = LEA64r %stack.1.r, 1, $noreg, 12, $noreg
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ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
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$rdi = COPY %4
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CALL64pcrel32 @inita, 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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%5:gr32 = COPY $eax
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LIFETIME_END %stack.1.r
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bb.4.return:
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RET 0
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...
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