Avoid adding PHI arguments for a predecessor that has gone away when a BRCOND was constant folded.

This fixes PR5980.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93184 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 97 insertions, 0 deletions

diff --git a/test/CodeGen/X86/2010-01-11-ExtraPHIArg.ll b/test/CodeGen/X86/2010-01-11-ExtraPHIArg.ll
new file mode 100644
index 0000000000..db98eef30e
--- /dev/null
+++ b/test/CodeGen/X86/2010-01-11-ExtraPHIArg.ll
@@ -0,0 +1,97 @@
+; RUN: llc -verify-machineinstrs < %s
+;
+; The lowering of a switch combined with constand folding would leave spurious extra arguments on a PHI instruction.
+;
+target triple = "x86_64-apple-darwin10"
+
+define void @foo() {
+  br label %cond_true813.i
+
+cond_true813.i:                                   ; preds = %0
+  br i1 false, label %cond_true818.i, label %cond_next1146.i
+
+cond_true818.i:                                   ; preds = %cond_true813.i
+  br i1 false, label %recog_memoized.exit52, label %cond_next1146.i
+
+recog_memoized.exit52:                            ; preds = %cond_true818.i
+  switch i32 0, label %bb886.i.preheader [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i
+    i32 103, label %bb874.i
+    i32 114, label %bb874.i
+  ]
+
+bb857.i:                                          ; preds = %bb886.i, %bb866.i
+  %tmp862.i494.24 = phi i8* [ null, %bb866.i ], [ %tmp862.i494.26, %bb886.i ] ; <i8*> [#uses=1]
+  switch i32 0, label %bb886.i.preheader [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i
+    i32 103, label %bb874.i
+    i32 114, label %bb874.i
+  ]
+
+bb866.i.loopexit:                                 ; preds = %bb874.i
+  br label %bb866.i
+
+bb866.i.loopexit31:                               ; preds = %cond_true903.i
+  br label %bb866.i
+
+bb866.i:                                          ; preds = %bb866.i.loopexit31, %bb866.i.loopexit, %bb857.i, %recog_memoized.exit52
+  br i1 false, label %bb907.i, label %bb857.i
+
+bb874.i.preheader.loopexit:                       ; preds = %cond_true903.i, %cond_true903.i
+  ret void
+
+bb874.i:                                          ; preds = %bb857.i, %bb857.i, %recog_memoized.exit52, %recog_memoized.exit52
+  switch i32 0, label %bb886.i.preheader.loopexit [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i.loopexit
+    i32 103, label %bb874.i.backedge
+    i32 114, label %bb874.i.backedge
+  ]
+
+bb874.i.backedge:                                 ; preds = %bb874.i, %bb874.i
+  ret void
+
+bb886.i.preheader.loopexit:                       ; preds = %bb874.i
+  ret void
+
+bb886.i.preheader:                                ; preds = %bb857.i, %recog_memoized.exit52
+  %tmp862.i494.26 = phi i8* [ undef, %recog_memoized.exit52 ], [ %tmp862.i494.24, %bb857.i ] ; <i8*> [#uses=1]
+  br label %bb886.i
+
+bb886.i:                                          ; preds = %cond_true903.i, %bb886.i.preheader
+  br i1 false, label %bb857.i, label %cond_true903.i
+
+cond_true903.i:                                   ; preds = %bb886.i
+  switch i32 0, label %bb886.i [
+    i32 0, label %bb907.i
+    i32 44, label %bb866.i.loopexit31
+    i32 103, label %bb874.i.preheader.loopexit
+    i32 114, label %bb874.i.preheader.loopexit
+  ]
+
+bb907.i:                                          ; preds = %cond_true903.i, %bb874.i, %bb866.i, %bb857.i, %recog_memoized.exit52
+  br i1 false, label %cond_next1146.i, label %cond_true910.i
+
+cond_true910.i:                                   ; preds = %bb907.i
+  ret void
+
+cond_next1146.i:                                  ; preds = %bb907.i, %cond_true818.i, %cond_true813.i
+  ret void
+
+bb2060.i:                                         ; No predecessors!
+  br i1 false, label %cond_true2064.i, label %bb2067.i
+
+cond_true2064.i:                                  ; preds = %bb2060.i
+  unreachable
+
+bb2067.i:                                         ; preds = %bb2060.i
+  ret void
+
+cond_next3473:                                    ; No predecessors!
+  ret void
+
+cond_next3521:                                    ; No predecessors!
+  ret void
+}