[PATCH] [AArch64] Enable generating TBZ/TBNZ

[Z. Zheng]

Hi Jiangning, t.p.northover,

This is one of the optimizations we ported from ARM64 to AArch64 to address the performance gap between these two back ends. Please help review.

http://reviews.llvm.org/D3321

Files:
  lib/Target/AArch64/AArch64ISelLowering.cpp
  test/CodeGen/AArch64/andCmpBrToTBZ.ll

Index: lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- lib/Target/AArch64/AArch64ISelLowering.cpp
+++ lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -540,6 +540,8 @@
 
   setTargetDAGCombine(ISD::SIGN_EXTEND);
   setTargetDAGCombine(ISD::VSELECT);
+
+  MaskAndBranchFoldingIsLegal = true;
 }
 
 EVT AArch64TargetLowering::getSetCCResultType(LLVMContext &, EVT VT) const {
Index: test/CodeGen/AArch64/andCmpBrToTBZ.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/andCmpBrToTBZ.ll
@@ -0,0 +1,72 @@
+; RUN: llc -O1 -march=aarch64 -enable-andcmp-sinking=true < %s | FileCheck %s
+; ModuleID = 'and-cbz-extr-mr.bc'
+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-n32:64-S128"
+target triple = "aarch64-none-linux-gnu"
+
+define zeroext i1 @foo(i1 %IsEditable, i1 %isTextField, i8* %str1, i8* %str2, i8* %str3, i8* %str4, i8* %str5, i8* %str6, i8* %str7, i8* %str8, i8* %str9, i8* %str10, i8* %str11, i8* %str12, i8* %str13, i32 %int1, i8* %str14) unnamed_addr #0 align 2 {
+; CHECK: foo:
+entry:
+  %tobool = icmp eq i8* %str14, null
+  br i1 %tobool, label %return, label %if.end
+
+; CHECK: %if.end
+; CHECK: tbz
+if.end:                                           ; preds = %entry
+  %and.i.i.i = and i32 %int1, 4
+  %tobool.i.i.i = icmp eq i32 %and.i.i.i, 0
+  br i1 %tobool.i.i.i, label %if.end12, label %land.rhs.i
+
+land.rhs.i:                                       ; preds = %if.end
+  %cmp.i.i.i = icmp eq i8* %str12, %str13
+  br i1 %cmp.i.i.i, label %if.then3, label %lor.rhs.i.i.i
+
+lor.rhs.i.i.i:                                    ; preds = %land.rhs.i
+  %cmp.i13.i.i.i = icmp eq i8* %str10, %str11
+  br i1 %cmp.i13.i.i.i, label %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit, label %if.end5
+
+_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit: ; preds = %lor.rhs.i.i.i
+  %cmp.i.i.i.i = icmp eq i8* %str8, %str9
+  br i1 %cmp.i.i.i.i, label %if.then3, label %if.end5
+
+if.then3:                                         ; preds = %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit, %land.rhs.i
+  %tmp11 = load i8* %str14, align 8
+  %tmp12 = and i8 %tmp11, 2
+  %tmp13 = icmp ne i8 %tmp12, 0
+  br label %return
+
+if.end5:                                          ; preds = %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit, %lor.rhs.i.i.i
+; CHECK: %if.end5
+; CHECK: tbz
+  br i1 %tobool.i.i.i, label %if.end12, label %land.rhs.i19
+
+land.rhs.i19:                                     ; preds = %if.end5
+  %cmp.i.i.i18 = icmp eq i8* %str6, %str7
+  br i1 %cmp.i.i.i18, label %if.then7, label %lor.rhs.i.i.i23
+
+lor.rhs.i.i.i23:                                  ; preds = %land.rhs.i19
+  %cmp.i13.i.i.i22 = icmp eq i8* %str3, %str4
+  br i1 %cmp.i13.i.i.i22, label %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit28, label %if.end12
+
+_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit28: ; preds = %lor.rhs.i.i.i23
+  %cmp.i.i.i.i26 = icmp eq i8* %str1, %str2
+  br i1 %cmp.i.i.i.i26, label %if.then7, label %if.end12
+
+if.then7:                                         ; preds = %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit28, %land.rhs.i19
+  br i1 %isTextField, label %if.then9, label %if.end12
+
+if.then9:                                         ; preds = %if.then7
+  %tmp23 = load i8* %str5, align 8
+  %tmp24 = and i8 %tmp23, 2
+  %tmp25 = icmp ne i8 %tmp24, 0
+  br label %return
+
+if.end12:                                         ; preds = %if.then7, %_ZNK7WebCore4Node10hasTagNameERKNS_13QualifiedNameE.exit28, %lor.rhs.i.i.i23, %if.end5, %if.end
+  %lnot = xor i1 %IsEditable, true
+  br label %return
+
+return:                                           ; preds = %if.end12, %if.then9, %if.then3, %entry
+  %retval.0 = phi i1 [ %tmp13, %if.then3 ], [ %tmp25, %if.then9 ], [ %lnot, %if.end12 ], [ true, %entry ]
+  ret i1 %retval.0
+}
+
+attributes #0 = { nounwind ssp }
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