[llvm] r291740 - Make a test actually test what it set out to test.

[Chandler Carruth via llvm-commits]

Author: chandlerc
Date: Wed Jan 11 21:49:07 2017
New Revision: 291740

URL: http://llvm.org/viewvc/llvm-project?rev=291740&view=rev
Log:
Make a test actually test what it set out to test.

This test seems to have largely been relying on asserts being tripped.
It had a very specific and somewhat uninteresting grep of the output,
but it never really did anything to cause SCEV to be preserved across
loop simplify, certainly not explicitly. And a later addition to it
actually added CHECK lines despite the test never running FileCheck.

Now we actually print SCEV before and after loop simplify to make sure
it is *changing* and being *updated*. Which seems to be much more likely
the point of the test.

Modified:
    llvm/trunk/test/Transforms/LoopSimplify/preserve-scev.ll

Modified: llvm/trunk/test/Transforms/LoopSimplify/preserve-scev.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplify/preserve-scev.ll?rev=291740&r1=291739&r2=291740&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplify/preserve-scev.ll (original)
+++ llvm/trunk/test/Transforms/LoopSimplify/preserve-scev.ll Wed Jan 11 21:49:07 2017
@@ -1,14 +1,38 @@
-; RUN: opt -S < %s -indvars | opt -analyze -iv-users | grep "%cmp = icmp slt i32" | grep "= {%\.ph,+,1}<%for.cond>"
-; PR8079
+; RUN: opt -S < %s -analyze -scalar-evolution -loop-simplify -scalar-evolution | FileCheck %s
 
 ; Provide legal integer types.
 target datalayout = "n8:16:32:64"
 
-; LoopSimplify should invalidate indvars when splitting out the
-; inner loop.
-
 @maxStat = external global i32
 
+; LoopSimplify should invalidate SCEV when splitting out the
+; inner loop.
+;
+; First SCEV print:
+; CHECK-LABEL: Classifying expressions for: @test
+; CHECK: %[[PHI:.*]] = phi i32 [ 0, %entry ], [ %{{.*}}, %if.then5 ], [ %[[PHI]], %if.end ]
+; CHECK-LABEL: Determining loop execution counts for: @test
+; CHECK: Loop %for.body18: Unpredictable backedge-taken count.
+; CHECK: Loop %for.body18: Unpredictable max backedge-taken count.
+; CHECK: Loop %for.body18: Unpredictable predicated backedge-taken count.
+; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %for.cond: Unpredictable max backedge-taken count.
+; CHECK: Loop %for.cond: Unpredictable predicated backedge-taken count.
+;
+; Now simplify the loop, which should cause SCEV to re-compute more precise
+; info here in addition to having preheader PHIs. Second SCEV print:
+; CHECK-LABEL: Classifying expressions for: @test
+; CHECK: phi i32 [ %{{.*}}, %if.then5 ], [ 0, %entry ]
+; CHECK-LABEL: Determining loop execution counts for: @test
+; CHECK: Loop %for.body18: Unpredictable backedge-taken count.
+; CHECK: Loop %for.body18: Unpredictable max backedge-taken count.
+; CHECK: Loop %for.body18: Unpredictable predicated backedge-taken count.
+; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %for.cond: max backedge-taken count is -2147483647
+; CHECK: Loop %for.cond: Unpredictable predicated backedge-taken count.
+; CHECK: Loop %for.cond.outer: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %for.cond.outer: Unpredictable max backedge-taken count.
+; CHECK: Loop %for.cond.outer: Unpredictable predicated backedge-taken count.
 define i32 @test() nounwind {
 entry:
   br label %for.cond
@@ -52,12 +76,27 @@ return:
 
 declare void @foo() nounwind
 
-; Notify SCEV when removing an ExitingBlock.
-; CHECK-LABEL: @mergeExit(
-; CHECK: while.cond191:
-; CHECK: br i1 %or.cond, label %while.body197
-; CHECK-NOT: land.rhs:
-; CHECK: ret
+; Notify SCEV when removing an ExitingBlock. This only changes the
+; backedge-taken information.
+;
+; First SCEV print:
+; CHECK-LABEL: Determining loop execution counts for: @mergeExit
+; CHECK: Loop %while.cond191: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %while.cond191: max backedge-taken count is -1
+; CHECK: Loop %while.cond191: Unpredictable predicated backedge-taken count.
+; CHECK: Loop %while.cond191.outer: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %while.cond191.outer: Unpredictable max backedge-taken count.
+; CHECK: Loop %while.cond191.outer: Unpredictable predicated backedge-taken count.
+;
+; After simplifying, the max backedge count is refined.
+; Second SCEV print:
+; CHECK-LABEL: Determining loop execution counts for: @mergeExit
+; CHECK: Loop %while.cond191: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %while.cond191: max backedge-taken count is 0
+; CHECK: Loop %while.cond191: Unpredictable predicated backedge-taken count.
+; CHECK: Loop %while.cond191.outer: <multiple exits> Unpredictable backedge-taken count.
+; CHECK: Loop %while.cond191.outer: Unpredictable max backedge-taken count.
+; CHECK: Loop %while.cond191.outer: Unpredictable predicated backedge-taken count.
 define void @mergeExit(i32 %MapAttrCount) nounwind uwtable ssp {
 entry:
   br i1 undef, label %if.then124, label %if.end126