[llvm] r333416 - StackColoring: better handling of statically unreachable code
Than McIntosh via llvm-commits
llvm-commits at lists.llvm.org
Tue May 29 06:52:24 PDT 2018
Author: thanm
Date: Tue May 29 06:52:24 2018
New Revision: 333416
URL: http://llvm.org/viewvc/llvm-project?rev=333416&view=rev
Log:
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
Added:
llvm/trunk/test/CodeGen/X86/PR37310.mir
Modified:
llvm/trunk/lib/CodeGen/StackColoring.cpp
Modified: llvm/trunk/lib/CodeGen/StackColoring.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StackColoring.cpp?rev=333416&r1=333415&r2=333416&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/StackColoring.cpp (original)
+++ llvm/trunk/lib/CodeGen/StackColoring.cpp Tue May 29 06:52:24 2018
@@ -782,8 +782,11 @@ void StackColoring::calculateLocalLivene
for (MachineBasicBlock::const_pred_iterator PI = BB->pred_begin(),
PE = BB->pred_end(); PI != PE; ++PI) {
LivenessMap::const_iterator I = BlockLiveness.find(*PI);
- assert(I != BlockLiveness.end() && "Predecessor not found");
- LocalLiveIn |= I->second.LiveOut;
+ // PR37130: transformations prior to stack coloring can
+ // sometimes leave behind statically unreachable blocks; these
+ // can be safely skipped here.
+ if (I != BlockLiveness.end())
+ LocalLiveIn |= I->second.LiveOut;
}
// Compute LiveOut by subtracting out lifetimes that end in this
Added: llvm/trunk/test/CodeGen/X86/PR37310.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/PR37310.mir?rev=333416&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/PR37310.mir (added)
+++ llvm/trunk/test/CodeGen/X86/PR37310.mir Tue May 29 06:52:24 2018
@@ -0,0 +1,153 @@
+# RUN: llc -mtriple=x86_64-unknown-linux-gnu -mcpu=corei7 -start-before dwarfehprepare -no-stack-coloring=false -stop-after stack-coloring -o - %s
+
+# Test to insure that the liveness analysis in the StackColoring
+# pass gracefully handles statically unreachable blocks. See PR 37310.
+
+# This MIR testcase was created by compiling the following test, first
+# with "clang -emit-llvm -S" and then "llc -stop-before stack-coloring",
+# and finally editing the resulting MIR by hand to introduce a statically
+# unreachable BB (to wit: rename all bb.3 to bb.4, rename bb.2 to bb.3,
+# then add bb.2 with unconditional jump to bb.4).
+
+# Original C code:
+# extern int inita(int *);
+# void foo(int x) {
+# if (x != 3) {
+# int q[128];
+# inita(&q[0]);
+# return;
+# }
+# int r[128];
+# inita(&r[x]);
+# }
+
+--- |
+
+ define void @foo(i32 %x) {
+ entry:
+ %q = alloca [128 x i32], align 16
+ %r = alloca [128 x i32], align 16
+ %cmp = icmp eq i32 %x, 3
+ br i1 %cmp, label %if.end, label %if.then
+
+ if.then: ; preds = %entry
+ %0 = bitcast [128 x i32]* %q to i8*
+ call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %0)
+ %arrayidx2 = bitcast [128 x i32]* %q to i32*
+ %call = call i32 @inita(i32* nonnull %arrayidx2)
+ call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %0)
+ br label %return
+
+ unreachable:
+ br label %return
+
+ if.end: ; preds = %entry
+ %1 = bitcast [128 x i32]* %r to i8*
+ call void @llvm.lifetime.start.p0i8(i64 512, i8* nonnull %1)
+ %arrayidx1 = getelementptr inbounds [128 x i32], [128 x i32]* %r, i64 0, i64 3
+ %call2 = call i32 @inita(i32* nonnull %arrayidx1)
+ call void @llvm.lifetime.end.p0i8(i64 512, i8* nonnull %1)
+ br label %return
+
+ return: ; preds = %if.end, %if.then
+ ret void
+ }
+
+ declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
+
+ declare i32 @inita(i32*)
+
+ declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
+
+ declare void @llvm.stackprotector(i8*, i8**)
+
+...
+---
+name: foo
+alignment: 4
+exposesReturnsTwice: false
+legalized: false
+regBankSelected: false
+selected: false
+failedISel: false
+tracksRegLiveness: true
+registers:
+ - { id: 0, class: gr32, preferred-register: '' }
+ - { id: 1, class: gr32, preferred-register: '' }
+ - { id: 2, class: gr64, preferred-register: '' }
+ - { id: 3, class: gr32, preferred-register: '' }
+ - { id: 4, class: gr64, preferred-register: '' }
+ - { id: 5, class: gr32, preferred-register: '' }
+liveins:
+ - { reg: '$edi', virtual-reg: '%0' }
+frameInfo:
+ isFrameAddressTaken: false
+ isReturnAddressTaken: false
+ hasStackMap: false
+ hasPatchPoint: false
+ stackSize: 0
+ offsetAdjustment: 0
+ maxAlignment: 16
+ adjustsStack: false
+ hasCalls: true
+ stackProtector: ''
+ maxCallFrameSize: 4294967295
+ hasOpaqueSPAdjustment: false
+ hasVAStart: false
+ hasMustTailInVarArgFunc: false
+ localFrameSize: 0
+ savePoint: ''
+ restorePoint: ''
+fixedStack:
+stack:
+ - { id: 0, name: q, type: default, offset: 0, size: 512, alignment: 16,
+ stack-id: 0, callee-saved-register: '', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, name: r, type: default, offset: 0, size: 512, alignment: 16,
+ stack-id: 0, callee-saved-register: '', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+constants:
+body: |
+ bb.0.entry:
+ successors: %bb.3(0x40000000), %bb.1(0x40000000)
+ liveins: $edi
+
+ %0:gr32 = COPY $edi
+ %1:gr32 = SUB32ri8 %0, 3, implicit-def $eflags
+ JE_1 %bb.3, implicit $eflags
+ JMP_1 %bb.1
+
+ bb.1.if.then:
+ successors: %bb.4(0x80000000)
+
+ LIFETIME_START %stack.0.q
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ %2:gr64 = LEA64r %stack.0.q, 1, $noreg, 0, $noreg
+ $rdi = COPY %2
+ CALL64pcrel32 @inita, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ %3:gr32 = COPY $eax
+ LIFETIME_END %stack.0.q
+ JMP_1 %bb.4
+
+ bb.2.unreachable:
+ successors: %bb.4(0x80000000)
+
+ JMP_1 %bb.4
+
+ bb.3.if.end:
+ successors: %bb.4(0x80000000)
+
+ LIFETIME_START %stack.1.r
+ %4:gr64 = LEA64r %stack.1.r, 1, $noreg, 12, $noreg
+ ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ $rdi = COPY %4
+ CALL64pcrel32 @inita, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax
+ ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+ %5:gr32 = COPY $eax
+ LIFETIME_END %stack.1.r
+
+ bb.4.return:
+ RET 0
+
+...
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