LSR fix: Add isSimplifiedLoopNest to IVUsers analysis.

Only record IVUsers that are dominated by simplified loop
headers. Otherwise SCEVExpander will crash while looking for a
preheader.

I previously tried to work around this in LSR itself, but that was
insufficient. This way, LSR can continue to run if some uses are not
in simple loops, as long as we don't attempt to analyze those users.

Fixes <rdar://problem/11049788> Segmentation fault: 11 in LoopStrengthReduce

llvm-svn: 152892

1 files changed, 50 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopStrengthReduce/2012-03-15-nopreheader.ll b/llvm/test/Transforms/LoopStrengthReduce/2012-03-15-nopreheader.ll
new file mode 100644
index 00000000000..207e9d74f5d
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/2012-03-15-nopreheader.ll
@@ -0,0 +1,50 @@
+; RUN: opt -loop-reduce -S < %s | FileCheck %s
+;
+; <rdar://problem/11049788> Segmentation fault: 11 in LoopStrengthReduce
+
+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"
+target triple = "x86_64-apple-darwin10.0.0"
+
+; IVUsers should not consider tmp128 a valid user because it is not in a
+; simplified loop nest.
+; CHECK: @nopreheader
+; CHECK: for.cond:
+; CHECK: %tmp128 = add i64 %0, %indvar65
+define void @nopreheader(i8* %cmd) nounwind ssp {
+entry:
+  indirectbr i8* undef, [label %while.cond]
+
+while.cond:                                       ; preds = %while.body, %entry
+  %0 = phi i64 [ %indvar.next48, %while.body ], [ 0, %entry ]
+  indirectbr i8* undef, [label %while.end, label %while.body]
+
+while.body:                                       ; preds = %lor.rhs, %lor.lhs.false17, %lor.lhs.false11, %lor.lhs.false, %land.rhs
+  %indvar.next48 = add i64 %0, 1
+  indirectbr i8* undef, [label %while.cond]
+
+while.end:                                        ; preds = %lor.rhs, %while.cond
+  indirectbr i8* undef, [label %if.end152]
+
+if.end152:                                        ; preds = %lor.lhs.false144, %if.end110
+  indirectbr i8* undef, [label %lor.lhs.false184, label %for.cond]
+
+lor.lhs.false184:                                 ; preds = %lor.lhs.false177
+  indirectbr i8* undef, [label %return, label %for.cond]
+
+for.cond:                                         ; preds = %for.inc, %lor.lhs.false184, %if.end152
+  %indvar65 = phi i64 [ %indvar.next66, %for.inc ], [ 0, %lor.lhs.false184 ], [ 0, %if.end152 ]
+  %tmp128 = add i64 %0, %indvar65
+  %s.4 = getelementptr i8* %cmd, i64 %tmp128
+  %tmp195 = load i8* %s.4, align 1
+  indirectbr i8* undef, [label %return, label %land.rhs198]
+
+land.rhs198:                                      ; preds = %for.cond
+  indirectbr i8* undef, [label %return, label %for.inc]
+
+for.inc:                                          ; preds = %lor.rhs234, %land.lhs.true228, %land.lhs.true216, %land.lhs.true204
+  %indvar.next66 = add i64 %indvar65, 1
+  indirectbr i8* undef, [label %for.cond]
+
+return:                                           ; preds = %if.end677, %doshell, %if.then96
+  ret void
+}