[polly] r309164 - [Simplify] Fix invalid removal write for escaping values.

[Michael Kruse via llvm-commits]

Author: meinersbur
Date: Wed Jul 26 12:58:15 2017
New Revision: 309164

URL: http://llvm.org/viewvc/llvm-project?rev=309164&view=rev
Log:
[Simplify] Fix invalid removal write for escaping values.

A PHI node's incoming block is the user of its operand, not the PHI's parent.

Assuming the PHINode's parent being the user lead to the removal of a
MemoryAccesses because its use was assumed to be inside of the SCoP.

Added:
    polly/trunk/test/Simplify/out-of-scop-use-in-region-entry-phi-node.ll
Modified:
    polly/trunk/lib/Support/VirtualInstruction.cpp

Modified: polly/trunk/lib/Support/VirtualInstruction.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Support/VirtualInstruction.cpp?rev=309164&r1=309163&r2=309164&view=diff
==============================================================================
--- polly/trunk/lib/Support/VirtualInstruction.cpp (original)
+++ polly/trunk/lib/Support/VirtualInstruction.cpp Wed Jul 26 12:58:15 2017
@@ -167,8 +167,8 @@ static bool isRoot(const Instruction *In
 /// removed in order for its value to be available after the SCoP.
 static bool isEscaping(Scop *S, Instruction *ComputingInst) {
   for (Use &Use : ComputingInst->uses()) {
-    Instruction *User = cast<Instruction>(Use.getUser());
-    if (!S->contains(User))
+    BasicBlock *UserBB = getUseBlock(Use);
+    if (!S->contains(UserBB))
       return true;
   }
   return false;

Added: polly/trunk/test/Simplify/out-of-scop-use-in-region-entry-phi-node.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Simplify/out-of-scop-use-in-region-entry-phi-node.ll?rev=309164&view=auto
==============================================================================
--- polly/trunk/test/Simplify/out-of-scop-use-in-region-entry-phi-node.ll (added)
+++ polly/trunk/test/Simplify/out-of-scop-use-in-region-entry-phi-node.ll Wed Jul 26 12:58:15 2017
@@ -0,0 +1,44 @@
+; RUN: opt %loadPolly -polly-scops -polly-simplify -analyze < %s | FileCheck %s
+;
+; %tmp5 must keep the Value WRITE MemoryAccess, because as an incoming value of
+; %tmp4, it is an "external use".
+;
+; A common mistake is to assume that %tmp5 is used by %tmp4 in bb3, when
+; practially it's the incoming block %bb9 which is the user.
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @hoge() {
+bb:
+  br label %bb2
+
+bb2:                                              ; preds = %bb
+  %tmp = load i64*, i64** undef
+  br label %bb3
+
+bb3:                                              ; preds = %bb9, %bb2
+  %tmp4 = phi i64* [ %tmp, %bb2 ], [ %tmp5, %bb9 ]
+  %tmp5 = getelementptr inbounds i64, i64* %tmp4, i64 1
+  %tmp6 = load i64, i64* %tmp5
+  %tmp7 = and i64 %tmp6, 4160749568
+  br i1 false, label %bb8, label %bb9
+
+bb8:                                              ; preds = %bb3
+  br label %bb9
+
+bb9:                                              ; preds = %bb8, %bb3
+  %tmp10 = icmp eq i64 %tmp7, 134217728
+  br i1 %tmp10, label %bb11, label %bb3
+
+bb11:                                             ; preds = %bb9
+  br label %bb12
+
+bb12:                                             ; preds = %bb11
+  ret void
+}
+
+
+; CHECK:      MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:     [p_0] -> { Stmt_bb3[] -> MemRef_tmp5[] };
+
+; CHECK: SCoP could not be simplified