[ScopInfo] Allow PHI nodes that reference an error block

As long as these PHI nodes are only referenced by terminator instructions.

llvm-svn: 314212

diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index 38b7be1..80e3058 100644 (file)
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -1184,8 +1184,17 @@ bool ScopDetection::isValidInstruction(Instruction &Inst,
     if (!OpInst)
       continue;
 
-    if (isErrorBlock(*OpInst->getParent(), Context.CurRegion, LI, DT))
-      return false;
+    if (isErrorBlock(*OpInst->getParent(), Context.CurRegion, LI, DT)) {
+      auto *PHI = dyn_cast<PHINode>(OpInst);
+      if (PHI) {
+        for (User *U : PHI->users()) {
+          if (!isa<TerminatorInst>(U))
+            return false;
+        }
+      } else {
+        return false;
+      }
+    }
   }
 
   if (isa<LandingPadInst>(&Inst) || isa<ResumeInst>(&Inst))

diff --git a/polly/test/ScopInfo/condition-after-error-block-2.ll b/polly/test/ScopInfo/condition-after-error-block-2.ll
new file mode 100644 (file)
index 0000000..4d8e176
--- /dev/null
+++ b/polly/test/ScopInfo/condition-after-error-block-2.ll
@@ -0,0 +1,62 @@
+; RUN: opt %loadPolly -polly-scops -analyze < %s | FileCheck %s
+
+; Verify that we do not allow PHI nodes such as %phi, if they reference an error
+; block and are used by anything else than a terminator instruction.
+
+; CHECK:      Statements {
+; CHECK-NEXT:  Stmt_loop
+; CHECK-NEXT:         Domain :=
+; CHECK-NEXT:             [p] -> { Stmt_loop[i0] : p >= 13 and 0 <= i0 <= 1025 };
+; CHECK-NEXT:         Schedule :=
+; CHECK-NEXT:             [p] -> { Stmt_loop[i0] -> [i0] };
+; CHECK-NEXT:         MustWriteAccess :=       [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:             [p] -> { Stmt_loop[i0] -> MemRef_X[0] };
+; CHECK-NEXT:         MustWriteAccess :=       [Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:             [p] -> { Stmt_loop[i0] -> MemRef_phi[] };
+; CHECK-NEXT: }
+
+declare void @bar()
+
+define void @foo(float* %X, i64 %p) {
+entry:
+  br label %br
+
+br:
+  %cmp1 = icmp sle i64 %p, 12
+  br i1 %cmp1, label %A, label %br2
+
+br2:
+  %cmp3 = icmp sle i64 %p, 12
+  br i1 %cmp3, label %cond, label %loop
+
+loop:
+  %indvar = phi i64 [0, %br2], [%indvar.next, %loop]
+  %indvar.next = add nsw i64 %indvar, 1
+  store float 41.0, float* %X
+  %cmp2 = icmp sle i64 %indvar, 1024
+  br i1 %cmp2, label %loop, label %merge
+
+cond:
+  br label %cond2
+
+cond2:
+  call void @bar()
+  br label %merge
+
+merge:
+  %phi = phi i1 [false, %cond2], [true, %loop]
+  %add = add i1 %phi, 1
+  br i1 %add, label %A, label %B
+
+A:
+  store float 42.0, float* %X
+  br label %exit
+
+B:
+  call void @bar()
+  store float 41.0, float* %X
+  br label %exit
+
+exit:
+  ret void
+}