When forgetting SCEVs for loop PHIs, don't forget SCEVUnknown values.

These values aren't analyzable, so they don't care if more information
about the loop trip count can be had. Also, SCEVUnknown is used for
a PHI while the PHI itself is being analyzed, so it needs to be left
in the Scalars map. This fixes a variety of subtle issues.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71533 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/IndVarSimplify/loop_evaluate_5.ll

@@ -0,0 +1,32 @@
+; RUN: llvm-as < %s | opt -indvars | llvm-dis | grep {120, %bb2.bb3_crit_edge}
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64"
+target triple = "i686-pc-linux-gnu"
+
+; Indvars should be able to compute an exit value for %tmp1.
+
+define i32 @testcase(i5 zeroext %k) nounwind readnone {
+entry:
+	br i1 false, label %bb3, label %bb.nph
+
+bb.nph:		; preds = %entry
+	br label %bb
+
+bb:		; preds = %bb2, %bb.nph
+	%result2 = phi i32 [ %tmp1, %bb2 ], [ 0, %bb.nph ]		; <i32> [#uses=1]
+	%k_01 = phi i5 [ %indvar_next1, %bb2 ], [ 0, %bb.nph ]		; <i5> [#uses=2]
+	%tmp2 = zext i5 %k_01 to i32		; <i32> [#uses=1]
+	%tmp1 = add i32 %tmp2, %result2		; <i32> [#uses=2]
+	%indvar_next1 = add i5 %k_01, 1		; <i5> [#uses=2]
+	br label %bb2
+
+bb2:		; preds = %bb
+	%phitmp = icmp eq i5 %indvar_next1, -16		; <i1> [#uses=1]
+	br i1 %phitmp, label %bb2.bb3_crit_edge, label %bb
+
+bb2.bb3_crit_edge:		; preds = %bb2
+	br label %bb3
+
+bb3:		; preds = %bb2.bb3_crit_edge, %entry
+	%result.lcssa = phi i32 [ %tmp1, %bb2.bb3_crit_edge ], [ 0, %entry ]		; <i32> [#uses=1]
+	ret i32 %result.lcssa
+}