[llvm] r325287 - [X86] Use btc/btr/bts to implement xor/and/or that affects a single bit in the upper 32-bits of a 64-bit operation.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu Feb 15 11:57:35 2018
New Revision: 325287

URL: http://llvm.org/viewvc/llvm-project?rev=325287&view=rev
Log:
[X86] Use btc/btr/bts to implement xor/and/or that affects a single bit in the upper 32-bits of a 64-bit operation.

We can't fold a large immediate into a 64-bit operation. But if we know we're only operating on a single bit we can use the bit instructions.

For now only do this for optsize.

Differential Revision: https://reviews.llvm.org/D37418

Modified:
    llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
    llvm/trunk/lib/Target/X86/X86InstrCompiler.td
    llvm/trunk/lib/Target/X86/X86InstrInfo.td

Modified: llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp?rev=325287&r1=325286&r2=325287&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp Thu Feb 15 11:57:35 2018
@@ -368,6 +368,11 @@ namespace {
       return CurDAG->getTargetConstant(Imm, DL, MVT::i32);
     }
 
+    /// Return a target constant with the specified value, of type i64.
+    inline SDValue getI64Imm(uint64_t Imm, const SDLoc &DL) {
+      return CurDAG->getTargetConstant(Imm, DL, MVT::i64);
+    }
+
     SDValue getExtractVEXTRACTImmediate(SDNode *N, unsigned VecWidth,
                                         const SDLoc &DL) {
       assert((VecWidth == 128 || VecWidth == 256) && "Unexpected vector width");

Modified: llvm/trunk/lib/Target/X86/X86InstrCompiler.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrCompiler.td?rev=325287&r1=325286&r2=325287&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrCompiler.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrCompiler.td Thu Feb 15 11:57:35 2018
@@ -1471,6 +1471,37 @@ def : Pat<(and GR64:$src, 0xff),
 } // AddedComplexity = 1
 
 
+// Try to use BTS/BTR/BTC for single bit operations on the upper 32-bits.
+
+def BTRXForm : SDNodeXForm<imm, [{
+  // Transformation function: Find the lowest 0.
+  return getI64Imm((uint8_t)N->getAPIntValue().countTrailingOnes(), SDLoc(N));
+}]>;
+
+def BTCBTSXForm : SDNodeXForm<imm, [{
+  // Transformation function: Find the lowest 1.
+  return getI64Imm((uint8_t)N->getAPIntValue().countTrailingZeros(), SDLoc(N));
+}]>;
+
+def BTRMask64 : ImmLeaf<i64, [{
+  return !isUInt<32>(Imm) && !isInt<32>(Imm) && isPowerOf2_64(~Imm);
+}]>;
+
+def BTCBTSMask64 : ImmLeaf<i64, [{
+  return !isInt<32>(Imm) && isPowerOf2_64(Imm);
+}]>;
+
+// For now only do this for optsize.
+let AddedComplexity = 1, Predicates=[OptForSize] in {
+  def : Pat<(and GR64:$src1, BTRMask64:$mask),
+            (BTR64ri8 GR64:$src1, (BTRXForm imm:$mask))>;
+  def : Pat<(or GR64:$src1, BTCBTSMask64:$mask),
+            (BTS64ri8 GR64:$src1, (BTCBTSXForm imm:$mask))>;
+  def : Pat<(xor GR64:$src1, BTCBTSMask64:$mask),
+            (BTC64ri8 GR64:$src1, (BTCBTSXForm imm:$mask))>;
+}
+
+
 // sext_inreg patterns
 def : Pat<(sext_inreg GR32:$src, i16),
           (MOVSX32rr16 (EXTRACT_SUBREG GR32:$src, sub_16bit))>;

Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.td?rev=325287&r1=325286&r2=325287&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.td Thu Feb 15 11:57:35 2018
@@ -2407,7 +2407,7 @@ def BEXTRMaskXForm : SDNodeXForm<imm, [{
 }]>;
 
 def AndMask64 : ImmLeaf<i64, [{
-  return isMask_64(Imm) && Imm > UINT32_MAX;
+  return isMask_64(Imm) && !isUInt<32>(Imm);
 }]>;
 
 // Use BEXTR for 64-bit 'and' with large immediate 'mask'.