[llvm] r358108 - [AArch64] Teach getTestBitOperand to look through ANY_EXTENDS

[Craig Topper via llvm-commits]

Author: ctopper
Date: Wed Apr 10 10:27:29 2019
New Revision: 358108

URL: http://llvm.org/viewvc/llvm-project?rev=358108&view=rev
Log:
[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

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
    llvm/trunk/test/CodeGen/AArch64/tbz-tbnz.ll

Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp?rev=358108&r1=358107&r2=358108&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp Wed Apr 10 10:27:29 2019
@@ -11038,6 +11038,12 @@ static SDValue getTestBitOperand(SDValue
     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;
 

Modified: llvm/trunk/test/CodeGen/AArch64/tbz-tbnz.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/tbz-tbnz.ll?rev=358108&r1=358107&r2=358108&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/tbz-tbnz.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/tbz-tbnz.ll Wed Apr 10 10:27:29 2019
@@ -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()