diff options
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 15 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/selectcc-to-shiftand.ll | 12 |
2 files changed, 16 insertions, 11 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 377c6086b1a..41303921d87 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -8221,10 +8221,11 @@ SDValue DAGCombiner::foldSelectOfConstants(SDNode *N) { return Cond; } - // For any constants that differ by 1, we can transform the select into an - // extend and add. Use a target hook because some targets may prefer to - // transform in the other direction. + // Use a target hook because some targets may prefer to transform in the + // other direction. if (TLI.convertSelectOfConstantsToMath(VT)) { + // For any constants that differ by 1, we can transform the select into an + // extend and add. const APInt &C1Val = C1->getAPIntValue(); const APInt &C2Val = C2->getAPIntValue(); if (C1Val - 1 == C2Val) { @@ -8239,6 +8240,14 @@ SDValue DAGCombiner::foldSelectOfConstants(SDNode *N) { Cond = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, Cond); return DAG.getNode(ISD::ADD, DL, VT, Cond, N2); } + + // select Cond, Pow2, 0 --> (zext Cond) << log2(Pow2) + if (C1Val.isPowerOf2() && C2Val.isNullValue()) { + if (VT != MVT::i1) + Cond = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Cond); + SDValue ShAmtC = DAG.getConstant(C1Val.exactLogBase2(), DL, VT); + return DAG.getNode(ISD::SHL, DL, VT, Cond, ShAmtC); + } } return SDValue(); diff --git a/llvm/test/CodeGen/X86/selectcc-to-shiftand.ll b/llvm/test/CodeGen/X86/selectcc-to-shiftand.ll index 52cda558c7c..5e58cde9b05 100644 --- a/llvm/test/CodeGen/X86/selectcc-to-shiftand.ll +++ b/llvm/test/CodeGen/X86/selectcc-to-shiftand.ll @@ -202,19 +202,15 @@ define i32 @PR31175(i32 %x, i32 %y) { define i8 @sel_shift_bool_i8(i1 %t) { ; CHECK-NOBMI-LABEL: sel_shift_bool_i8: ; CHECK-NOBMI: # %bb.0: -; CHECK-NOBMI-NEXT: # kill: def $edi killed $edi def $rdi -; CHECK-NOBMI-NEXT: notb %dil -; CHECK-NOBMI-NEXT: shlb $7, %dil -; CHECK-NOBMI-NEXT: leal -128(%rdi), %eax +; CHECK-NOBMI-NEXT: movl %edi, %eax +; CHECK-NOBMI-NEXT: shlb $7, %al ; CHECK-NOBMI-NEXT: # kill: def $al killed $al killed $eax ; CHECK-NOBMI-NEXT: retq ; ; CHECK-BMI-LABEL: sel_shift_bool_i8: ; CHECK-BMI: # %bb.0: -; CHECK-BMI-NEXT: # kill: def $edi killed $edi def $rdi -; CHECK-BMI-NEXT: notb %dil -; CHECK-BMI-NEXT: shlb $7, %dil -; CHECK-BMI-NEXT: leal -128(%rdi), %eax +; CHECK-BMI-NEXT: movl %edi, %eax +; CHECK-BMI-NEXT: shlb $7, %al ; CHECK-BMI-NEXT: # kill: def $al killed $al killed $eax ; CHECK-BMI-NEXT: retq %shl = select i1 %t, i8 128, i8 0 |
