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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2023-02-28 11:00:35 -0600 |
|---|---|---|
| committer | Tom Stellard <tstellar@redhat.com> | 2023-03-03 23:53:12 -0800 |
| commit | f5f4825b189ccb016e01a9cd10e2a06cd8f2a89a (patch) | |
| tree | 235c4e50b42834bf94aba4cc0f2f70e041757b72 | |
| parent | da0580260e83e7354f82e0abdc5f4f65a6a2e6c1 (diff) | |
| download | llvm-f5f4825b189ccb016e01a9cd10e2a06cd8f2a89a.tar.gz | |
[X86] Fix `(shift X, (xor Y, N-1))` -> `(shift X, (not Y))` by properly inserting `not Y` into DAG. [#61038]
Previously not inserting the `-1` in `not Y` (`xor Y, -1`) into the
DAG. Not inserting `-1` as a DAG node comes up as a bug when doing
`(xor (shl 1, A), B)` -> `(btc A, B)`. `btc` requires `B` (dst) to be
a register.
Differential Revision: https://reviews.llvm.org/D144984
(cherry picked from commit 4a23031fac1a58f6cf05d07f915633930532eafa)
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelDAGToDAG.cpp | 5 | ||||
| -rw-r--r-- | llvm/test/CodeGen/X86/pr61038.ll | 48 |
2 files changed, 52 insertions, 1 deletions
diff --git a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp index d69e2c3ed493..181de6abb2c5 100644 --- a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp +++ b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp @@ -4020,7 +4020,10 @@ bool X86DAGToDAGISel::tryShiftAmountMod(SDNode *N) { EVT OpVT = ShiftAmt.getValueType(); - NewShiftAmt = CurDAG->getNOT(DL, Add0C == nullptr ? Add0 : Add1, OpVT); + SDValue AllOnes = CurDAG->getAllOnesConstant(DL, OpVT); + NewShiftAmt = CurDAG->getNode(ISD::XOR, DL, OpVT, + Add0C == nullptr ? Add0 : Add1, AllOnes); + insertDAGNode(*CurDAG, OrigShiftAmt, AllOnes); insertDAGNode(*CurDAG, OrigShiftAmt, NewShiftAmt); // If we are shifting by N-X where N == 0 mod Size, then just shift by // -X to generate a NEG instead of a SUB of a constant. diff --git a/llvm/test/CodeGen/X86/pr61038.ll b/llvm/test/CodeGen/X86/pr61038.ll new file mode 100644 index 000000000000..2db78234b3be --- /dev/null +++ b/llvm/test/CodeGen/X86/pr61038.ll @@ -0,0 +1,48 @@ +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py +; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=skylake-avx512 | FileCheck %s --check-prefix=CHECK-BMI2 +; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v4 | FileCheck %s --check-prefix=CHECK-BMI2 +; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+bmi | FileCheck %s --check-prefix=CHECK-BMI + +declare i32 @llvm.cttz.i32(i32, i1 immarg) +define void @test_61038(ptr %tmp_buffer) { +; CHECK-BMI2-LABEL: test_61038: +; CHECK-BMI2: # %bb.0: # %entry +; CHECK-BMI2-NEXT: tzcntl %eax, %eax +; CHECK-BMI2-NEXT: movabsq $8589934591, %rcx # imm = 0x1FFFFFFFF +; CHECK-BMI2-NEXT: movq $-1, %rdx +; CHECK-BMI2-NEXT: btcq %rax, %rdx +; CHECK-BMI2-NEXT: shrxq %rdx, %rcx, %rdx +; CHECK-BMI2-NEXT: btcq %rax, %rcx +; CHECK-BMI2-NEXT: xorl %eax, %eax +; CHECK-BMI2-NEXT: cmpq $64, %rcx +; CHECK-BMI2-NEXT: cmovael %eax, %edx +; CHECK-BMI2-NEXT: movl %edx, (%rdi) +; CHECK-BMI2-NEXT: retq +; +; CHECK-BMI-LABEL: test_61038: +; CHECK-BMI: # %bb.0: # %entry +; CHECK-BMI-NEXT: tzcntl %eax, %eax +; CHECK-BMI-NEXT: movabsq $8589934591, %rdx # imm = 0x1FFFFFFFF +; CHECK-BMI-NEXT: movq %rdx, %rsi +; CHECK-BMI-NEXT: btcq %rax, %rsi +; CHECK-BMI-NEXT: movq $-1, %rcx +; CHECK-BMI-NEXT: btcq %rax, %rcx +; CHECK-BMI-NEXT: # kill: def $cl killed $cl killed $rcx +; CHECK-BMI-NEXT: shrq %cl, %rdx +; CHECK-BMI-NEXT: xorl %eax, %eax +; CHECK-BMI-NEXT: cmpq $64, %rsi +; CHECK-BMI-NEXT: cmovael %eax, %edx +; CHECK-BMI-NEXT: movl %edx, (%rdi) +; CHECK-BMI-NEXT: retq +entry: + %0 = tail call i32 @llvm.cttz.i32(i32 poison, i1 false) + %1 = zext i32 %0 to i64 + %2 = shl nuw nsw i64 1, %1 + %3 = xor i64 %2, 8589934591 + %4 = icmp ugt i64 %3, 63 + %x11.op.i = lshr i64 8589934591, %3 + %5 = trunc i64 %x11.op.i to i32 + %6 = select i1 %4, i32 0, i32 %5 + store i32 %6, ptr %tmp_buffer, align 4 + ret void +} |