indvars: fixed IV cloning in -disable-iv-rewrite mode with associated

cleanup and overdue test cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132038 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/IndVarSimplify/elim-extend.ll

@@ -0,0 +1,93 @@
+; RUN: opt < %s -indvars -disable-iv-rewrite -S | FileCheck %s
+
+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"
+
+; Tests sign extend elimination in the inner and outer loop.
+; %outercount is straightforward to widen, besides being in an outer loop.
+; %innercount is currently blocked by lcssa, so is not widened.
+; %inneriv can be widened only after proving it has no signed-overflow
+;   based on the loop test.
+define void @nestedIV(i8* %address, i32 %limit) nounwind {
+entry:
+  %limitdec = add i32 %limit, -1
+  br label %outerloop
+
+; CHECK: outerloop:
+;
+; Eliminate %ofs1 after widening outercount.
+; CHECK-NOT: sext
+; CHECK: getelementptr
+;
+; IV rewriting hoists a gep into this block. We don't like that.
+; CHECK-NOT: getelementptr
+outerloop:
+  %outercount   = phi i32 [ %outerpostcount, %outermerge ], [ 0, %entry ]
+  %innercount = phi i32 [ %innercount.merge, %outermerge ], [ 0, %entry ]
+
+  %outercountdec = add i32 %outercount, -1
+  %ofs1 = sext i32 %outercountdec to i64
+  %adr1 = getelementptr i8* %address, i64 %ofs1
+  store i8 0, i8* %adr1
+
+  br label %innerpreheader
+
+innerpreheader:
+  %innerprecmp = icmp sgt i32 %limitdec, %innercount
+  br i1 %innerprecmp, label %innerloop, label %outermerge
+
+; CHECK: innerloop:
+;
+; Eliminate %ofs2 after widening inneriv.
+; CHECK-NOT: sext
+; CHECK: getelementptr
+;
+; FIXME: We should not increase the number of IVs in this loop.
+; sext elimination plus LFTR results in 3 final IVs.
+;
+; FIXME: eliminate %ofs3 based the loop pre/post conditions
+; even though innerpostiv is not NSW, thus sign extending innerpostiv
+; does not yield the same expression as incrementing the widened inneriv.
+innerloop:
+  %inneriv = phi i32 [ %innerpostiv, %innerloop ], [ %innercount, %innerpreheader ]
+  %innerpostiv = add i32 %inneriv, 1
+
+  %ofs2 = sext i32 %inneriv to i64
+  %adr2 = getelementptr i8* %address, i64 %ofs2
+  store i8 0, i8* %adr2
+
+  %ofs3 = sext i32 %innerpostiv to i64
+  %adr3 = getelementptr i8* %address, i64 %ofs3
+  store i8 0, i8* %adr3
+
+  %innercmp = icmp sgt i32 %limitdec, %innerpostiv
+  br i1 %innercmp, label %innerloop, label %innerexit
+
+innerexit:
+  %innercount.lcssa = phi i32 [ %innerpostiv, %innerloop ]
+  br label %outermerge
+
+; CHECK: outermerge:
+;
+; Eliminate %ofs4 after widening outercount
+; CHECK-NOT: sext
+; CHECK: getelementptr
+;
+; TODO: Eliminate %ofs5 after removing lcssa
+outermerge:
+  %innercount.merge = phi i32 [ %innercount.lcssa, %innerexit ], [ %innercount, %innerpreheader ]
+
+  %ofs4 = sext i32 %outercount to i64
+  %adr4 = getelementptr i8* %address, i64 %ofs4
+  store i8 0, i8* %adr3
+
+  %ofs5 = sext i32 %innercount.merge to i64
+  %adr5 = getelementptr i8* %address, i64 %ofs5
+  store i8 0, i8* %adr4
+
+  %outerpostcount = add i32 %outercount, 1
+  %tmp47 = icmp slt i32 %outerpostcount, %limit
+  br i1 %tmp47, label %outerloop, label %return
+
+return:
+  ret void
+}