[llvm-commits] [llvm] r133034 - in /llvm/trunk: lib/Target/ARM/ARMISelLowering.cpp test/CodeGen/ARM/bfi.ll

[Evan Cheng]

Author: evancheng
Date: Tue Jun 14 20:12:31 2011
New Revision: 133034

URL: http://llvm.org/viewvc/llvm-project?rev=133034&view=rev
Log:
PerformBFICombine - (bfi A, (and B, Mask1), Mask2) -> (bfi A, B, Mask2) iff
the bits being cleared by the AND are not demanded by the BFI.

The previous BFI dag combine rule was actually incorrect (or used to be
correct until BFI representation changed).

rdar://9609030

Modified:
    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
    llvm/trunk/test/CodeGen/ARM/bfi.ll

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=133034&r1=133033&r2=133034&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Tue Jun 14 20:12:31 2011
@@ -5976,8 +5976,8 @@
   return SDValue();
 }
 
-/// PerformBFICombine - (bfi A, (and B, C1), C2) -> (bfi A, B, C2) iff
-/// C1 & C2 == C1.
+/// PerformBFICombine - (bfi A, (and B, Mask1), Mask2) -> (bfi A, B, Mask2) iff
+/// the bits being cleared by the AND are not demanded by the BFI.
 static SDValue PerformBFICombine(SDNode *N,
                                  TargetLowering::DAGCombinerInfo &DCI) {
   SDValue N1 = N->getOperand(1);
@@ -5985,9 +5985,12 @@
     ConstantSDNode *N11C = dyn_cast<ConstantSDNode>(N1.getOperand(1));
     if (!N11C)
       return SDValue();
-    unsigned Mask = cast<ConstantSDNode>(N->getOperand(2))->getZExtValue();
+    unsigned InvMask = cast<ConstantSDNode>(N->getOperand(2))->getZExtValue();
+    unsigned LSB = CountTrailingZeros_32(~InvMask);
+    unsigned Width = (32 - CountLeadingZeros_32(~InvMask)) - LSB;
+    unsigned Mask = (1 << Width)-1;
     unsigned Mask2 = N11C->getZExtValue();
-    if ((Mask & Mask2) == Mask2)
+    if ((Mask & (~Mask2)) == 0)
       return DCI.DAG.getNode(ARMISD::BFI, N->getDebugLoc(), N->getValueType(0),
                              N->getOperand(0), N1.getOperand(0),
                              N->getOperand(2));

Modified: llvm/trunk/test/CodeGen/ARM/bfi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/bfi.ll?rev=133034&r1=133033&r2=133034&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/bfi.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/bfi.ll Tue Jun 14 20:12:31 2011
@@ -61,3 +61,16 @@
   %3 = or i32 %2, %0
   ret i32 %3
 }
+
+; rdar://9609030
+define i32 @f6(i32 %a, i32 %b) nounwind readnone {
+entry:
+; CHECK: f6:
+; CHECK-NOT: bic
+; CHECK: bfi r0, r1, #8, #9
+  %and = and i32 %a, -130817
+  %and2 = shl i32 %b, 8
+  %shl = and i32 %and2, 130816
+  %or = or i32 %shl, %and
+  ret i32 %or
+}