Fix the LoopUnroller to handle nontrivial loops and partial unrolling.

These are not individual bug fixes. I had to rewrite a good chunk of
the unroller to make it sane. I think it was getting lucky on trivial
completely unrolled loops with no early exits. I included some fairly
simple unit tests for partial unrolling. I didn't do much stress
testing, so it may not be perfect, but should be usable now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137190 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 62 insertions, 0 deletions

diff --git a/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll b/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll
new file mode 100644
index 0000000000..c1221f595a
--- /dev/null
+++ b/test/Transforms/LoopUnroll/2011-08-09-PhiUpdate.ll
@@ -0,0 +1,62 @@
+; RUN: opt -S < %s -instcombine -inline -jump-threading -loop-unroll -unroll-count=4 | FileCheck %s
+;
+; This is a test case that required a number of setup passes because
+; it depends on block order.
+
+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-macosx10.6.8"
+
+declare i1 @check() nounwind
+declare i32 @getval() nounwind
+
+; Check that the loop exit merges values from all the iterations. This
+; could be a tad fragile, but it's a good test.
+;
+; CHECK: @foo
+; CHECK: return:
+; CHECK: %retval.0 = phi i32 [ %tmp7.i, %land.lhs.true ], [ 0, %do.cond ], [ %tmp7.i.1, %land.lhs.true.1 ], [ 0, %do.cond.1 ], [ %tmp7.i.2, %land.lhs.true.2 ], [ 0, %do.cond.2 ], [ %tmp7.i.3, %land.lhs.true.3 ], [ 0, %do.cond.3 ]
+; CHECK-NOT: @bar
+; CHECK: bar.exit.3
+define i32 @foo() uwtable ssp align 2 {
+entry:
+  br i1 undef, label %return, label %if.end
+
+if.end:                                           ; preds = %entry
+  %call2 = call i32 @getval()
+  br label %do.body
+
+do.body:                                          ; preds = %do.cond, %if.end
+  %call6 = call i32 @bar()
+  %cmp = icmp ne i32 %call6, 0
+  br i1 %cmp, label %land.lhs.true, label %do.cond
+
+land.lhs.true:                                    ; preds = %do.body
+  %call10 = call i32 @getval()
+  %cmp11 = icmp eq i32 0, %call10
+  br i1 %cmp11, label %return, label %do.cond
+
+do.cond:                                          ; preds = %land.lhs.true, %do.body
+  %cmp18 = icmp sle i32 0, %call2
+  br i1 %cmp18, label %do.body, label %return
+
+return:                                           ; preds = %do.cond, %land.lhs.true, %entry
+  %retval.0 = phi i32 [ 0, %entry ], [ %call6, %land.lhs.true ], [ 0, %do.cond ]
+  ret i32 %retval.0
+}
+
+define linkonce_odr i32 @bar() nounwind uwtable ssp align 2 {
+entry:
+  br i1 undef, label %land.lhs.true, label %cond.end
+
+land.lhs.true:                                    ; preds = %entry
+  %cmp4 = call zeroext i1 @check()
+  br i1 %cmp4, label %cond.true, label %cond.end
+
+cond.true:                                        ; preds = %land.lhs.true
+  %tmp7 = call i32 @getval()
+  br label %cond.end
+
+cond.end:                                         ; preds = %cond.true, %land.lhs.true, %entry
+  %cond = phi i32 [ %tmp7, %cond.true ], [ 0, %land.lhs.true ], [ 0, %entry ]
+  ret i32 %cond
+}