LSR Fix: check SCEV expression safety before expansion.

All SCEV expressions used by LSR formulae must be safe to
expand. i.e. they may not contain UDiv unless we can prove nonzero
denominator.

Fixes PR11356: LSR hoists UDiv.

llvm-svn: 160205

1 files changed, 90 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopStrengthReduce/2012-07-13-ExpandUDiv.ll b/llvm/test/Transforms/LoopStrengthReduce/2012-07-13-ExpandUDiv.ll
new file mode 100644
index 00000000000..a1222083abc
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/2012-07-13-ExpandUDiv.ll
@@ -0,0 +1,90 @@
+; RUN: opt -loop-reduce -S < %s | FileCheck %s
+;
+; PR11356: likely wrong code bug
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-darwin"
+
+@g_66 = global [1 x i32] zeroinitializer, align 4
+@g_775 = global i32 0, align 4
+@g_752 = global i32 0, align 4
+@g_3 = global i32 0, align 4
+
+; Ensure that %div.i.i.us is not hoisted.
+; CHECK: @main
+; CHECK: for.body.i.i.us:
+; CHECK: %div.i.i.i.us
+; CHECK: %cmp5.i.i.us
+define i32 @main() nounwind uwtable ssp {
+entry:
+  %l_2 = alloca [1 x i32], align 4
+  %arrayidx = getelementptr inbounds [1 x i32]* %l_2, i64 0, i64 0
+  store i32 0, i32* %arrayidx, align 4, !tbaa !0
+  %tmp = load i32* @g_3, align 4, !tbaa !0
+  %idxprom = sext i32 %tmp to i64
+  %arrayidx1 = getelementptr inbounds [1 x i32]* %l_2, i64 0, i64 %idxprom
+  %tmp1 = load i32* %arrayidx1, align 4, !tbaa !0
+  %conv.i.i = and i32 %tmp1, 65535
+  %tobool.i.i.i = icmp ne i32 %tmp, 0
+  br label %codeRepl
+
+codeRepl.loopexit.us-lcssa:                       ; preds = %for.body.i.i, %codeRepl5
+  br label %codeRepl.loopexit
+
+codeRepl.loopexit:                                ; preds = %codeRepl.loopexit.us-lcssa.us, %codeRepl.loopexit.us-lcssa
+  br label %codeRepl
+
+codeRepl:                                         ; preds = %codeRepl.loopexit, %entry
+  br i1 %tobool.i.i.i, label %codeRepl.split.us, label %codeRepl.codeRepl.split_crit_edge
+
+codeRepl.codeRepl.split_crit_edge:                ; preds = %codeRepl
+  br label %codeRepl.split
+
+codeRepl.split.us:                                ; preds = %codeRepl
+  br label %for.cond.i.i.us
+
+for.cond.i.i.us:                                  ; preds = %for.inc.i.i.us, %codeRepl.split.us
+  %tmp2 = phi i32 [ 0, %codeRepl.split.us ], [ %add.i.i.us, %for.inc.i.i.us ]
+  br label %codeRepl5.us
+
+for.inc.i.i.us:                                   ; preds = %for.body.i.i.us
+  %add.i.i.us = add nsw i32 %tmp2, 1
+  store i32 %add.i.i.us, i32* @g_752, align 4, !tbaa !0
+  br label %for.cond.i.i.us
+
+for.body.i.i.us:                                  ; preds = %codeRepl5.us
+  %div.i.i.i.us = udiv i32 1, %conv.i.i
+  %cmp5.i.i.us = icmp eq i32 %div.i.i.i.us, %tmp2
+  br i1 %cmp5.i.i.us, label %codeRepl.loopexit.us-lcssa.us, label %for.inc.i.i.us
+
+codeRepl5.us:                                     ; preds = %for.cond.i.i.us
+  br i1 true, label %codeRepl.loopexit.us-lcssa.us, label %for.body.i.i.us
+
+codeRepl.loopexit.us-lcssa.us:                    ; preds = %codeRepl5.us, %for.body.i.i.us
+  br label %codeRepl.loopexit
+
+codeRepl.split:                                   ; preds = %codeRepl.codeRepl.split_crit_edge
+  br label %for.cond.i.i
+
+for.cond.i.i:                                     ; preds = %for.inc.i.i, %codeRepl.split
+  %tmp3 = phi i32 [ 0, %codeRepl.split ], [ %add.i.i, %for.inc.i.i ]
+  br label %codeRepl5
+
+codeRepl5:                                        ; preds = %for.cond.i.i
+  br i1 true, label %codeRepl.loopexit.us-lcssa, label %for.body.i.i
+
+for.body.i.i:                                     ; preds = %codeRepl5
+  %cmp5.i.i = icmp eq i32 0, %tmp3
+  br i1 %cmp5.i.i, label %codeRepl.loopexit.us-lcssa, label %for.inc.i.i
+
+for.inc.i.i:                                      ; preds = %for.body.i.i
+  %add.i.i = add nsw i32 %tmp3, 1
+  store i32 %add.i.i, i32* @g_752, align 4, !tbaa !0
+  br label %for.cond.i.i
+
+func_4.exit:                                      ; No predecessors!
+  ret i32 0
+}
+
+!0 = metadata !{metadata !"int", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA", null}