When pruning candidate formulae out of an LSRUse, update the

LSRUse's Regs set after all pruning is done, rather than trying
to do it on the fly, which can produce an incomplete result.

This fixes a case where heuristic pruning was stripping all
formulae from a use, which led the solver to enter an infinite
loop.

Also, add a few asserts to diagnose this kind of situation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103328 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 83 insertions, 0 deletions

diff --git a/test/CodeGen/X86/lsr-delayed-fold.ll b/test/CodeGen/X86/lsr-delayed-fold.ll
index 17d6a4c091..8afbb0d7a3 100644
--- a/test/CodeGen/X86/lsr-delayed-fold.ll
+++ b/test/CodeGen/X86/lsr-delayed-fold.ll
@@ -49,3 +49,86 @@ lbl_264:                                          ; preds = %if.end, %lbl_264.pr
   %tobool12 = icmp eq i8 %mul.i18, 0              ; <i1> [#uses=1]
   unreachable
 }
+
+; LSR ends up going into conservative pruning mode; don't prune the solution
+; so far that it becomes unsolvable though.
+; PR7077
+
+%struct.Bu = type { i32, i32, i32 }
+
+define void @_Z3fooP2Bui(%struct.Bu* nocapture %bu) {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.inc131, %entry
+  %indvar = phi i64 [ %indvar.next, %for.inc131 ], [ 0, %entry ] ; <i64> [#uses=3]
+  br i1 undef, label %for.inc131, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %for.body
+  %tmp15 = add i64 %indvar, 1                     ; <i64> [#uses=1]
+  %tmp17 = add i64 %indvar, 2                      ; <i64> [#uses=1]
+  %tmp19 = add i64 %indvar, 3                      ; <i64> [#uses=1]
+  %tmp21 = add i64 %indvar, 4                      ; <i64> [#uses=1]
+  %tmp23 = add i64 %indvar, 5                      ; <i64> [#uses=1]
+  %tmp25 = add i64 %indvar, 6                      ; <i64> [#uses=1]
+  %tmp27 = add i64 %indvar, 7                      ; <i64> [#uses=1]
+  %tmp29 = add i64 %indvar, 8                      ; <i64> [#uses=1]
+  %tmp31 = add i64 %indvar, 9                      ; <i64> [#uses=1]
+  %tmp35 = add i64 %indvar, 11                     ; <i64> [#uses=1]
+  %tmp37 = add i64 %indvar, 12                     ; <i64> [#uses=1]
+  %tmp39 = add i64 %indvar, 13                     ; <i64> [#uses=1]
+  %tmp41 = add i64 %indvar, 14                     ; <i64> [#uses=1]
+  %tmp43 = add i64 %indvar, 15                     ; <i64> [#uses=1]
+  %tmp45 = add i64 %indvar, 16                     ; <i64> [#uses=1]
+  %tmp47 = add i64 %indvar, 17                     ; <i64> [#uses=1]
+  %mul = trunc i64 %indvar to i32                  ; <i32> [#uses=1]
+  %add22 = trunc i64 %tmp15 to i32                ; <i32> [#uses=1]
+  %add28 = trunc i64 %tmp17 to i32                ; <i32> [#uses=1]
+  %add34 = trunc i64 %tmp19 to i32                ; <i32> [#uses=1]
+  %add40 = trunc i64 %tmp21 to i32                ; <i32> [#uses=1]
+  %add46 = trunc i64 %tmp23 to i32                ; <i32> [#uses=1]
+  %add52 = trunc i64 %tmp25 to i32                ; <i32> [#uses=1]
+  %add58 = trunc i64 %tmp27 to i32                ; <i32> [#uses=1]
+  %add64 = trunc i64 %tmp29 to i32                ; <i32> [#uses=1]
+  %add70 = trunc i64 %tmp31 to i32                ; <i32> [#uses=1]
+  %add82 = trunc i64 %tmp35 to i32                ; <i32> [#uses=1]
+  %add88 = trunc i64 %tmp37 to i32                ; <i32> [#uses=1]
+  %add94 = trunc i64 %tmp39 to i32                ; <i32> [#uses=1]
+  %add100 = trunc i64 %tmp41 to i32               ; <i32> [#uses=1]
+  %add106 = trunc i64 %tmp43 to i32               ; <i32> [#uses=1]
+  %add112 = trunc i64 %tmp45 to i32               ; <i32> [#uses=1]
+  %add118 = trunc i64 %tmp47 to i32               ; <i32> [#uses=1]
+  %tmp10 = getelementptr %struct.Bu* %bu, i64 %indvar, i32 2 ; <i32*> [#uses=1]
+  %tmp11 = load i32* %tmp10                       ; <i32> [#uses=0]
+  tail call void undef(i32 %add22)
+  tail call void undef(i32 %add28)
+  tail call void undef(i32 %add34)
+  tail call void undef(i32 %add40)
+  tail call void undef(i32 %add46)
+  tail call void undef(i32 %add52)
+  tail call void undef(i32 %add58)
+  tail call void undef(i32 %add64)
+  tail call void undef(i32 %add70)
+  tail call void undef(i32 %add82)
+  tail call void undef(i32 %add88)
+  tail call void undef(i32 %add94)
+  tail call void undef(i32 %add100)
+  tail call void undef(i32 %add106)
+  tail call void undef(i32 %add112)
+  tail call void undef(i32 %add118)
+  br label %for.body123
+
+for.body123:                                      ; preds = %for.body123, %lor.lhs.false
+  %j.03 = phi i32 [ 0, %lor.lhs.false ], [ %inc, %for.body123 ] ; <i32> [#uses=2]
+  %add129 = add i32 %mul, %j.03                   ; <i32> [#uses=1]
+  tail call void undef(i32 %add129)
+  %inc = add nsw i32 %j.03, 1                     ; <i32> [#uses=1]
+  br i1 undef, label %for.inc131, label %for.body123
+
+for.inc131:                                       ; preds = %for.body123, %for.body
+  %indvar.next = add i64 %indvar, 1               ; <i64> [#uses=1]
+  br i1 undef, label %for.end134, label %for.body
+
+for.end134:                                       ; preds = %for.inc131
+  ret void
+}