LSR: prune undesirable formulae early.

It's always good to prune early, but formulae that are unsatisfactory
in their own right need to be removed before running any other pruning
heuristics. We easily avoid generating such formulae, but we need them
as an intermediate basis for forming other good formulae.

llvm-svn: 145906

1 files changed, 96 insertions, 0 deletions

diff --git a/llvm/test/Transforms/LoopStrengthReduce/2011-12-04-loserreg.ll b/llvm/test/Transforms/LoopStrengthReduce/2011-12-04-loserreg.ll
new file mode 100644
index 00000000000..51086509627
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/2011-12-04-loserreg.ll
@@ -0,0 +1,96 @@
+; RUN: llc < %s | FileCheck %s
+;
+; Test LSR's ability to prune formulae that refer to nonexistant
+; AddRecs in other loops.
+;
+; Unable to reduce this case further because it requires LSR to exceed
+; ComplexityLimit.
+;
+; We really just want to ensure that LSR can process this loop without
+; finding an unsatisfactory solution and bailing out. I've added
+; dummyout, an obvious candidate for postinc replacement so we can
+; verify that LSR removes it.
+
+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-S128"
+target triple = "x86_64-apple-darwin"
+
+; CHECK: @test
+; CHECK: # %for.body{{$}}
+; dummyiv copy should be removed
+; CHECK-NOT: movq
+; CHECK: # %for.cond19.preheader
+; dummycnt should be removed
+; CHECK-NOT: incq
+; CHECK: # %for.body23{{$}}
+define i64 @test(i64 %count, float* nocapture %srcrow, i32* nocapture %destrow) nounwind uwtable ssp {
+entry:
+  %cmp34 = icmp eq i64 %count, 0
+  br i1 %cmp34, label %for.end29, label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %dummyiv = phi i64 [ %dummycnt, %for.body ], [ 0, %entry ]
+  %indvars.iv39 = phi i64 [ %indvars.iv.next40, %for.body ], [ 0, %entry ]
+  %dp.036 = phi i32* [ %add.ptr, %for.body ], [ %destrow, %entry ]
+  %p.035 = phi float* [ %incdec.ptr4, %for.body ], [ %srcrow, %entry ]
+  %incdec.ptr = getelementptr inbounds float* %p.035, i64 1
+  %0 = load float* %incdec.ptr, align 4
+  %incdec.ptr2 = getelementptr inbounds float* %p.035, i64 2
+  %1 = load float* %incdec.ptr2, align 4
+  %incdec.ptr3 = getelementptr inbounds float* %p.035, i64 3
+  %2 = load float* %incdec.ptr3, align 4
+  %incdec.ptr4 = getelementptr inbounds float* %p.035, i64 4
+  %3 = load float* %incdec.ptr4, align 4
+  %4 = load i32* %dp.036, align 4
+  %conv5 = fptoui float %0 to i32
+  %or = or i32 %4, %conv5
+  %arrayidx6 = getelementptr inbounds i32* %dp.036, i64 1
+  %5 = load i32* %arrayidx6, align 4
+  %conv7 = fptoui float %1 to i32
+  %or8 = or i32 %5, %conv7
+  %arrayidx9 = getelementptr inbounds i32* %dp.036, i64 2
+  %6 = load i32* %arrayidx9, align 4
+  %conv10 = fptoui float %2 to i32
+  %or11 = or i32 %6, %conv10
+  %arrayidx12 = getelementptr inbounds i32* %dp.036, i64 3
+  %7 = load i32* %arrayidx12, align 4
+  %conv13 = fptoui float %3 to i32
+  %or14 = or i32 %7, %conv13
+  store i32 %or, i32* %dp.036, align 4
+  store i32 %or8, i32* %arrayidx6, align 4
+  store i32 %or11, i32* %arrayidx9, align 4
+  store i32 %or14, i32* %arrayidx12, align 4
+  %add.ptr = getelementptr inbounds i32* %dp.036, i64 4
+  %indvars.iv.next40 = add i64 %indvars.iv39, 4
+  %dummycnt = add i64 %dummyiv, 1
+  %cmp = icmp ult i64 %indvars.iv.next40, %count
+  br i1 %cmp, label %for.body, label %for.cond19.preheader
+
+for.cond19.preheader:                             ; preds = %for.body
+  %dummyout = add i64 %dummyiv, 1
+  %rem = and i64 %count, 3
+  %cmp2130 = icmp eq i64 %rem, 0
+  br i1 %cmp2130, label %for.end29, label %for.body23.lr.ph
+
+for.body23.lr.ph:                                 ; preds = %for.cond19.preheader
+  %8 = and i64 %count, 3
+  br label %for.body23
+
+for.body23:                                       ; preds = %for.body23, %for.body23.lr.ph
+  %indvars.iv = phi i64 [ 0, %for.body23.lr.ph ], [ %indvars.iv.next, %for.body23 ]
+  %dp.132 = phi i32* [ %add.ptr, %for.body23.lr.ph ], [ %incdec.ptr28, %for.body23 ]
+  %p.131 = phi float* [ %incdec.ptr4, %for.body23.lr.ph ], [ %incdec.ptr24, %for.body23 ]
+  %incdec.ptr24 = getelementptr inbounds float* %p.131, i64 1
+  %9 = load float* %incdec.ptr24, align 4
+  %10 = load i32* %dp.132, align 4
+  %conv25 = fptoui float %9 to i32
+  %or26 = or i32 %10, %conv25
+  store i32 %or26, i32* %dp.132, align 4
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %incdec.ptr28 = getelementptr inbounds i32* %dp.132, i64 1
+  %exitcond = icmp eq i64 %indvars.iv.next, %8
+  br i1 %exitcond, label %for.end29, label %for.body23
+
+for.end29:                                        ; preds = %entry, %for.body23, %for.cond19.preheader
+  %result = phi i64 [ 0, %entry ], [ %dummyout, %for.body23 ], [ %dummyout, %for.cond19.preheader ]
+  ret i64 %result
+}