[LLE] Add missed LoopSimplify dependence

The code assumed that we always had a preheader without making the pass
dependent on LoopSimplify.

Thanks to Mattias Eriksson V for reporting this.

llvm-svn: 263173

2 files changed, 36 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
index e4419113d45..a0486901190 100644
--- a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
@@ -28,6 +28,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include <forward_list>
 
@@ -557,6 +558,7 @@ public:
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequiredID(LoopSimplifyID);
     AU.addRequired<LoopInfoWrapperPass>();
     AU.addPreserved<LoopInfoWrapperPass>();
     AU.addRequired<LoopAccessAnalysis>();
@@ -577,6 +579,7 @@ INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
 INITIALIZE_PASS_END(LoopLoadElimination, LLE_OPTION, LLE_name, false, false)
 
 namespace llvm {
diff --git a/llvm/test/Transforms/LoopLoadElim/loop-simplify-dep.ll b/llvm/test/Transforms/LoopLoadElim/loop-simplify-dep.ll
new file mode 100644
index 00000000000..f6bfe96d9c9
--- /dev/null
+++ b/llvm/test/Transforms/LoopLoadElim/loop-simplify-dep.ll
@@ -0,0 +1,33 @@
+; RUN: opt -loop-load-elim -S < %s | FileCheck %s
+
+; Make sure we create a preheader if we dont' have one.
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @f(i32* noalias nocapture %A, i32* noalias nocapture readonly %B, i64 %N, i1 %C) {
+entry:
+  br i1 %C, label %for.body, label %for.end
+
+; CHECK: for.body.preheader:
+; CHECK-NEXT: %load_initial = load i32, i32* %A
+; CHECK-NEXT: br label %for.body
+
+; CHECK: for.body:
+for.body:
+; CHECK-NEXT: %store_forwarded = phi i32 [ %load_initial, %for.body.preheader ], [ %add, %for.body ]
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
+  %load = load i32, i32* %arrayidx, align 4
+  %arrayidx2 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
+  %load_1 = load i32, i32* %arrayidx2, align 4
+; CHECK: %add = add i32 %load_1, %store_forwarded
+  %add = add i32 %load_1, %load
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %arrayidx_next = getelementptr inbounds i32, i32* %A, i64 %indvars.iv.next
+  store i32 %add, i32* %arrayidx_next, align 4
+  %exitcond = icmp eq i64 %indvars.iv.next, %N
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:
+  ret void
+}