Remove non-executed statements during SCoP simplifcation

  A statement with an empty domain complicates the invariant load
  hoisting and does not help any subsequent analysis or transformation.
  In fact it might introduce parameter dimensions or increase the
  schedule dimensionality. To this end, we remove statements with an
  empty domain early in the SCoP simplification.

llvm-svn: 249276

1 files changed, 52 insertions, 0 deletions

diff --git a/polly/test/ScopInfo/variant_load_empty_domain.ll b/polly/test/ScopInfo/variant_load_empty_domain.ll
new file mode 100644
index 00000000000..d42d24818f3
--- /dev/null
+++ b/polly/test/ScopInfo/variant_load_empty_domain.ll
@@ -0,0 +1,52 @@
+; RUN: opt %loadPolly -polly-scops -polly-detect-unprofitable -analyze < %s | FileCheck %s
+;
+; CHECK:      Invariant Accesses: {
+; CHECK-NEXT: }
+;
+; CHECK-NOT: Stmt_if_then
+;
+;
+;    void f(int *A) {
+;      for (int i = 1; i < 10; i++) {
+;        A[i]++;
+;        if (i > 10)
+;          A[i] += A[0];
+;      }
+;    }
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @f(i32* %A) {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 1, %entry ]
+  %exitcond = icmp ne i64 %indvars.iv, 10
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
+  %tmp = load i32, i32* %arrayidx, align 4
+  %inc = add nsw i32 %tmp, 1
+  store i32 %inc, i32* %arrayidx, align 4
+  br i1 false, label %if.then, label %if.end
+
+if.then:                                          ; preds = %for.body
+  %tmp1 = load i32, i32* %A, align 4
+  %arrayidx4 = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
+  %tmp2 = load i32, i32* %arrayidx4, align 4
+  %add = add nsw i32 %tmp2, %tmp1
+  store i32 %add, i32* %arrayidx4, align 4
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %for.body
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.end
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}