Simplify [su]max(MAX, n) to MAX. This comes up in loop tripcount

computations in loops with multiple exits.

Adjust the testcase for PR4436 so that the relevant portion isn't
optimized away.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74073 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 63 insertions, 0 deletions

diff --git a/test/Transforms/IndVarSimplify/loop_evaluate8.ll b/test/Transforms/IndVarSimplify/loop_evaluate8.ll
new file mode 100644
index 0000000..fa2f9e5
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/loop_evaluate8.ll
@@ -0,0 +1,63 @@
+; RUN: llvm-as < %s | opt -indvars | llvm-dis | not grep select
+
+; This loop has backedge-taken-count zero. Indvars shouldn't expand any
+; instructions to compute a trip count.
+
+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-f80:32:32"
+target triple = "i386-pc-linux-gnu"
+
+define i8* @string_expandtabs() nounwind {
+entry:
+	br i1 undef, label %bb33, label %bb1
+
+bb1:		; preds = %entry
+	br i1 undef, label %overflow1, label %bb15
+
+bb15:		; preds = %bb1
+	br i1 undef, label %bb33, label %bb17
+
+bb17:		; preds = %bb15
+	br label %bb30
+
+bb19:		; preds = %bb30
+	br i1 undef, label %bb20, label %bb29
+
+bb20:		; preds = %bb19
+	%0 = load i32* undef, align 4		; <i32> [#uses=1]
+	%1 = sub i32 %0, undef		; <i32> [#uses=1]
+	br label %bb23
+
+bb21:		; preds = %bb23
+	%2 = icmp ult i8* %q.0, undef		; <i1> [#uses=1]
+	br i1 %2, label %bb22, label %overflow2
+
+bb22:		; preds = %bb21
+	%3 = getelementptr i8* %q.0, i32 1		; <i8*> [#uses=1]
+	br label %bb23
+
+bb23:		; preds = %bb22, %bb20
+	%i.2 = phi i32 [ %1, %bb20 ], [ %4, %bb22 ]		; <i32> [#uses=1]
+	%q.0 = phi i8* [ undef, %bb20 ], [ %3, %bb22 ]		; <i8*> [#uses=3]
+	%4 = add i32 %i.2, -1		; <i32> [#uses=2]
+	%5 = icmp eq i32 %4, -1		; <i1> [#uses=1]
+	br i1 %5, label %bb29, label %bb21
+
+bb29:		; preds = %bb23, %bb19
+	%q.1 = phi i8* [ undef, %bb19 ], [ %q.0, %bb23 ]		; <i8*> [#uses=0]
+	br label %bb30
+
+bb30:		; preds = %bb29, %bb17
+	br i1 undef, label %bb19, label %bb33
+
+overflow2:		; preds = %bb21
+	br i1 undef, label %bb32, label %overflow1
+
+bb32:		; preds = %overflow2
+	br label %overflow1
+
+overflow1:		; preds = %bb32, %overflow2, %bb1
+	ret i8* null
+
+bb33:		; preds = %bb30, %bb15, %entry
+	ret i8* undef
+}