Allow PPC B and BLR to be if-converted into some predicated forms

This enables us to form predicated branches (which are the same conditional
branches we had before) and also a larger set of predicated returns (including
instructions like bdnzlr which is a conditional return and loop-counter
decrement all in one).

At the moment, if conversion does not capture all possible opportunities. A
simple example is provided in early-ret2.ll, where if conversion forms one
predicated return, and then the PPCEarlyReturn pass picks up the other one. So,
at least for now, we'll keep both mechanisms.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179134 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 89 insertions, 0 deletions

diff --git a/test/CodeGen/PowerPC/bdzlr.ll b/test/CodeGen/PowerPC/bdzlr.ll
new file mode 100644
index 0000000000..1d3b31ba10
--- /dev/null
+++ b/test/CodeGen/PowerPC/bdzlr.ll
@@ -0,0 +1,63 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | 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-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+%struct.lua_TValue.17.692 = type { %union.Value.16.691, i32 }
+%union.Value.16.691 = type { %union.GCObject.15.690* }
+%union.GCObject.15.690 = type { %struct.lua_State.14.689 }
+%struct.lua_State.14.689 = type { %union.GCObject.15.690*, i8, i8, i8, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.global_State.10.685*, %struct.CallInfo.11.686*, i32*, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.CallInfo.11.686*, %struct.CallInfo.11.686*, i32, i32, i16, i16, i8, i8, i32, i32, void (%struct.lua_State.14.689*, %struct.lua_Debug.12.687*)*, %struct.lua_TValue.17.692, %struct.lua_TValue.17.692, %union.GCObject.15.690*, %union.GCObject.15.690*, %struct.lua_longjmp.13.688*, i64 }
+%struct.global_State.10.685 = type { %struct.stringtable.0.675, i8* (i8*, i8*, i64, i64)*, i8*, i8, i8, i32, %union.GCObject.15.690*, %union.GCObject.15.690**, %union.GCObject.15.690*, %union.GCObject.15.690*, %union.GCObject.15.690*, %union.GCObject.15.690*, %struct.Mbuffer.1.676, i64, i64, i64, i64, i32, i32, i32 (%struct.lua_State.14.689*)*, %struct.lua_TValue.17.692, %struct.lua_State.14.689*, %struct.UpVal.3.678, [9 x %struct.Table.7.682*], [17 x %union.TString.9.684*] }
+%struct.stringtable.0.675 = type { %union.GCObject.15.690**, i32, i32 }
+%struct.Mbuffer.1.676 = type { i8*, i64, i64 }
+%struct.UpVal.3.678 = type { %union.GCObject.15.690*, i8, i8, %struct.lua_TValue.17.692*, %union.anon.2.677 }
+%union.anon.2.677 = type { %struct.lua_TValue.17.692 }
+%struct.Table.7.682 = type { %union.GCObject.15.690*, i8, i8, i8, i8, %struct.Table.7.682*, %struct.lua_TValue.17.692*, %struct.Node.6.681*, %struct.Node.6.681*, %union.GCObject.15.690*, i32 }
+%struct.Node.6.681 = type { %struct.lua_TValue.17.692, %union.TKey.5.680 }
+%union.TKey.5.680 = type { %struct.anon.0.4.679 }
+%struct.anon.0.4.679 = type { %union.Value.16.691, i32, %struct.Node.6.681* }
+%union.TString.9.684 = type { %struct.anon.1.8.683 }
+%struct.anon.1.8.683 = type { %union.GCObject.15.690*, i8, i8, i8, i32, i64 }
+%struct.CallInfo.11.686 = type { %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, %struct.lua_TValue.17.692*, i32*, i32, i32 }
+%struct.lua_Debug.12.687 = type { i32, i8*, i8*, i8*, i8*, i32, i32, i32, i32, [60 x i8], i32 }
+%struct.lua_longjmp.13.688 = type opaque
+
+define void @lua_xmove(i32 signext %n) #0 {
+entry:
+  br i1 undef, label %for.end, label %if.end
+
+if.end:                                           ; preds = %entry
+  br i1 undef, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph:                                   ; preds = %if.end
+  br label %for.body
+
+for.body:                                         ; preds = %for.body.for.body_crit_edge, %for.body.lr.ph
+  %0 = phi %struct.lua_TValue.17.692* [ undef, %for.body.lr.ph ], [ %.pre, %for.body.for.body_crit_edge ]
+  %indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body.for.body_crit_edge ]
+  %tt = getelementptr inbounds %struct.lua_TValue.17.692* %0, i64 %indvars.iv, i32 1
+  %1 = load i32* %tt, align 4, !tbaa !0
+  store i32 %1, i32* undef, align 4, !tbaa !0
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %for.end, label %for.body.for.body_crit_edge
+
+for.body.for.body_crit_edge:                      ; preds = %for.body
+  %.pre = load %struct.lua_TValue.17.692** undef, align 8, !tbaa !3
+  br label %for.body
+
+for.end:                                          ; preds = %for.body, %if.end, %entry
+  ret void
+
+; CHECK: @lua_xmove
+; CHECK: bnelr
+; CHECK: bnelr
+; CHECK: bdzlr
+}
+
+attributes #0 = { nounwind }
+
+!0 = metadata !{metadata !"int", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA"}
+!3 = metadata !{metadata !"any pointer", metadata !1}
diff --git a/test/CodeGen/PowerPC/early-ret2.ll b/test/CodeGen/PowerPC/early-ret2.ll
new file mode 100644
index 0000000000..bedd16ce4d
--- /dev/null
+++ b/test/CodeGen/PowerPC/early-ret2.ll
@@ -0,0 +1,26 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | 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-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+define void @_Z8example3iPiS_() #0 {
+entry:
+  br i1 undef, label %while.end, label %while.body.lr.ph
+
+while.body.lr.ph:                                 ; preds = %entry
+  br i1 undef, label %while.end, label %while.body
+
+while.body:                                       ; preds = %while.body, %while.body.lr.ph
+  br i1 false, label %while.end, label %while.body, !llvm.vectorizer.already_vectorized !0
+
+while.end:                                        ; preds = %while.body, %while.body.lr.ph, %entry
+  ret void
+
+; CHECK: @_Z8example3iPiS_
+; CHECK: bnelr
+; CHECK: bnelr
+}
+
+attributes #0 = { noinline nounwind }
+
+!0 = metadata !{}
+