From 35fe07916aeae037c6e90ca9c384349c390bead4 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Wed, 10 Apr 2019 17:27:29 +0000
Subject: [PATCH] [AArch64] Teach getTestBitOperand to look through ANY_EXTENDS

This patch teach getTestBitOperand to look through ANY_EXTENDs when the extended bits aren't used. The test case changed here is based what D60358 did to test16 in tbz-tbnz.ll. So this patch will avoid that regression.

Differential Revision: https://reviews.llvm.org/D60482

llvm-svn: 358108
---
 llvm/lib/Target/AArch64/AArch64ISelLowering.cpp |  6 ++++++
 llvm/test/CodeGen/AArch64/tbz-tbnz.ll           | 15 ++++++++++-----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 84a66a2..f97fc40 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -11038,6 +11038,12 @@ static SDValue getTestBitOperand(SDValue Op, unsigned &Bit, bool &Invert,
     return getTestBitOperand(Op->getOperand(0), Bit, Invert, DAG);
   }
 
+  // (tbz (any_ext x), b) -> (tbz x, b) if we don't use the extended bits.
+  if (Op->getOpcode() == ISD::ANY_EXTEND &&
+      Bit < Op->getOperand(0).getValueSizeInBits()) {
+    return getTestBitOperand(Op->getOperand(0), Bit, Invert, DAG);
+  }
+
   if (Op->getNumOperands() != 2)
     return Op;
 
diff --git a/llvm/test/CodeGen/AArch64/tbz-tbnz.ll b/llvm/test/CodeGen/AArch64/tbz-tbnz.ll
index fa79250..5d6b390 100644
--- a/llvm/test/CodeGen/AArch64/tbz-tbnz.ll
+++ b/llvm/test/CodeGen/AArch64/tbz-tbnz.ll
@@ -360,17 +360,22 @@ end:
   ret void
 }
 
-define void @test20(i32 %in) {
-; CHECK-LABEL: @test20
+define void @test20(i32 %in) nounwind {
+; CHECK-LABEL: test20:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    tbnz w0, #2, .LBB19_2
+; CHECK-NEXT:  // %bb.1: // %then
+; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    bl t
+; CHECK-NEXT:    ldr x30, [sp], #16 // 8-byte Folded Reload
+; CHECK-NEXT:  .LBB19_2: // %end
+; CHECK-NEXT:    ret
   %shl = shl i32 %in, 3
   %zext = zext i32 %shl to i64
   %and = and i64 %zext, 32
   %cond = icmp eq i64 %and, 0
   br i1 %cond, label %then, label %end
 
-; FIXME: Should be no lsl
-; CHECK: lsl w8, w0, #3
-; CHECK: tbnz w8, #5
 
 then:
   call void @t()
-- 
2.7.4