[LAA] Hold bounds via ValueHandles during SCEV expansion

[oota-llvm.git] / test / Transforms / LoopDistribute / bounds-expansion-bug.ll

diff --git a/test/Transforms/LoopDistribute/bounds-expansion-bug.ll b/test/Transforms/LoopDistribute/bounds-expansion-bug.ll
new file mode 100644 (file)
index 0000000..5d1aac6
--- /dev/null
+++ b/test/Transforms/LoopDistribute/bounds-expansion-bug.ll
@@ -0,0 +1,106 @@
+; RUN: opt -basicaa -loop-distribute -S < %s | FileCheck %s
+
+; When emitting the memchecks for:
+;
+;   for (i = 0; i < n; i++) {
+;     A[i + 1] = A[i] * B[i];
+;     =======================
+;     C[i] = D[i] * E[i];
+;   }
+;
+; we had a bug when expanding the bounds for A and C.  These are expanded
+; multiple times and rely on the caching in SCEV expansion to avoid any
+; redundancy.  However, due to logic in SCEVExpander::ReuseOrCreateCast, we
+; can get earlier expanded values invalidated when casts are used.  This test
+; ensure that we are not using the invalidated values.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @f(i32* %a1, i32* %a2,
+               i32* %b,
+               i32* %c1, i32* %c2,
+               i32* %d,
+               i32* %e) {
+entry:
+
+  %cond = icmp eq i32* %e, null
+  br i1 %cond, label %one, label %two
+one:
+  br label %join
+two:
+  br label %join
+join:
+
+; The pointers need to be defined by PHIs in order for the bug to trigger.
+; Because of the PHIs the existing casts won't be at the desired location so a
+; new cast will be emitted and the old cast will get invalidated.
+;
+; These are the steps:
+;
+; 1. After the bounds for A and C are first expanded:
+;
+;   join:
+;     %a = phi i32* [ %a1, %one ], [ %a2, %two ]
+;     %c = phi i32* [ %c1, %one ], [ %c2, %two ]
+;     %c5 = bitcast i32* %c to i8*
+;     %a3 = bitcast i32* %a to i8*
+;
+; 2. After A is expanded again:
+;
+;   join:                                             ; preds = %two, %one
+;     %a = phi i32* [ %a1, %one ], [ %a2, %two ]
+;     %c = phi i32* [ %c1, %one ], [ %c2, %two ]
+;     %a3 = bitcast i32* %a to i8*                   <--- new
+;     %c5 = bitcast i32* %c to i8*
+;     %0 = bitcast i32* undef to i8*                 <--- old, invalidated
+;
+; 3. Finally, when C is expanded again:
+;
+;   join:                                             ; preds = %two, %one
+;     %a = phi i32* [ %a1, %one ], [ %a2, %two ]
+;     %c = phi i32* [ %c1, %one ], [ %c2, %two ]
+;     %c5 = bitcast i32* %c to i8*                   <--- new
+;     %a3 = bitcast i32* %a to i8*
+;     %0 = bitcast i32* undef to i8*                 <--- old, invalidated
+;     %1 = bitcast i32* undef to i8*
+
+  %a = phi i32* [%a1, %one], [%a2, %two]
+  %c = phi i32* [%c1, %one], [%c2, %two]
+  br label %for.body
+
+
+; CHECK: [[VALUE:%[0-9a-z]+]] = bitcast i32* undef to i8*
+; CHECK-NOT: [[VALUE]]
+
+for.body:                                         ; preds = %for.body, %entry
+  %ind = phi i64 [ 0, %join ], [ %add, %for.body ]
+
+  %arrayidxA = getelementptr inbounds i32, i32* %a, i64 %ind
+  %loadA = load i32, i32* %arrayidxA, align 4
+
+  %arrayidxB = getelementptr inbounds i32, i32* %b, i64 %ind
+  %loadB = load i32, i32* %arrayidxB, align 4
+
+  %mulA = mul i32 %loadB, %loadA
+
+  %add = add nuw nsw i64 %ind, 1
+  %arrayidxA_plus_4 = getelementptr inbounds i32, i32* %a, i64 %add
+  store i32 %mulA, i32* %arrayidxA_plus_4, align 4
+
+  %arrayidxD = getelementptr inbounds i32, i32* %d, i64 %ind
+  %loadD = load i32, i32* %arrayidxD, align 4
+
+  %arrayidxE = getelementptr inbounds i32, i32* %e, i64 %ind
+  %loadE = load i32, i32* %arrayidxE, align 4
+
+  %mulC = mul i32 %loadD, %loadE
+
+  %arrayidxC = getelementptr inbounds i32, i32* %c, i64 %ind
+  store i32 %mulC, i32* %arrayidxC, align 4
+
+  %exitcond = icmp eq i64 %add, 20
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}