ScopInfo: Do not try to model the memory accesses in an error block

Error blocks may contain arbitrary instructions, among them some which we can
not modeled correctly. As we do not generate ScopStmts for error blocks anyhow
there is no point in trying to generate access functions for them.

This fixes llvm.org/PR25494

llvm-svn: 252794

2 files changed, 39 insertions, 0 deletions

diff --git a/polly/lib/Analysis/ScopInfo.cpp b/polly/lib/Analysis/ScopInfo.cpp
index 68316588612..39ac622a3c7 100644
--- a/polly/lib/Analysis/ScopInfo.cpp
+++ b/polly/lib/Analysis/ScopInfo.cpp
@@ -3651,6 +3651,12 @@ void ScopInfo::buildStmts(Region &SR) {
 void ScopInfo::buildAccessFunctions(Region &R, BasicBlock &BB,
                                     Region *NonAffineSubRegion,
                                     bool IsExitBlock) {
+  // We do not build access functions for error blocks, as they may contain
+  // instructions we can not model.
+  DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+  if (isErrorBlock(BB, R, *LI, DT) && !IsExitBlock)
+    return;
+
   Loop *L = LI->getLoopFor(&BB);
 
   // The set of loops contained in non-affine subregions that are part of R.
diff --git a/polly/test/ScopInfo/do-not-model-error-block-accesses.ll b/polly/test/ScopInfo/do-not-model-error-block-accesses.ll
new file mode 100644
index 00000000000..a161afc9f26
--- /dev/null
+++ b/polly/test/ScopInfo/do-not-model-error-block-accesses.ll
@@ -0,0 +1,33 @@
+; RUN: opt %loadPolly -polly-scops -analyze < %s
+
+; Check that we do not crash on this input. Earlier this indeed crashed as
+; we tried to model the access functions in an error block.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Function Attrs: nounwind uwtable
+define void @FORMAT3_4() #0 {
+entry:
+  br label %entry.split
+
+entry.split:                                      ; preds = %entry
+  br i1 false, label %if.end.38, label %if.else
+
+if.else:                                          ; preds = %entry.split
+  call void (i32, i32, i32*, ...) bitcast (void (...)* @BYTES_TO_BITS to void (i32, i32, i32*, ...)*)(i32 undef, i32 1, i32* undef) #2
+  %0 = load i32, i32* null, align 4
+  br label %if.end.38
+
+if.end.38:                                        ; preds = %if.else, %entry.split
+  unreachable
+}
+
+declare void @BYTES_TO_BITS(...) #1
+
+attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="haswell" "target-features"="+aes,+avx,+avx2,+bmi,+bmi2,+cmov,+cx16,+f16c,+fma,+fsgsbase,+fxsr,+hle,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+rdrnd,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+xsave,+xsaveopt,-adx,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512pf,-avx512vl,-fma4,-prfchw,-rdseed,-sha,-sse4a,-tbm,-xop,-xsavec,-xsaves" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="haswell" "target-features"="+aes,+avx,+avx2,+bmi,+bmi2,+cmov,+cx16,+f16c,+fma,+fsgsbase,+fxsr,+hle,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+rdrnd,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+xsave,+xsaveopt,-adx,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512pf,-avx512vl,-fma4,-prfchw,-rdseed,-sha,-sse4a,-tbm,-xop,-xsavec,-xsaves" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 3.8.0 (http://llvm.org/git/clang.git 65eeefc97d2eee4d075ec7d9ed56b5f0786b6421)"}