[clang] [llvm] [SPIRV] Add PreLegalizer pattern matching for `faceforward` (PR #139959)
Kaitlin Peng via cfe-commits
cfe-commits at lists.llvm.org
Mon May 19 12:04:05 PDT 2025
================
@@ -98,21 +110,98 @@ void applySPIRVDistance(MachineInstr &MI, MachineRegisterInfo &MRI,
SPIRVGlobalRegistry *GR =
MI.getMF()->getSubtarget<SPIRVSubtarget>().getSPIRVGlobalRegistry();
- auto RemoveAllUses = [&](Register Reg) {
- SmallVector<MachineInstr *, 4> UsesToErase(
- llvm::make_pointer_range(MRI.use_instructions(Reg)));
-
- // calling eraseFromParent to early invalidates the iterator.
- for (auto *MIToErase : UsesToErase) {
- GR->invalidateMachineInstr(MIToErase);
- MIToErase->eraseFromParent();
- }
- };
- RemoveAllUses(SubDestReg); // remove all uses of FSUB Result
+ removeAllUses(SubDestReg, MRI, GR); // remove all uses of FSUB Result
GR->invalidateMachineInstr(SubInstr);
SubInstr->eraseFromParent(); // remove FSUB instruction
}
+/// This match is part of a combine that
+/// rewrites select(fcmp(dot(I, Ng), 0), N, 0 - N) to faceforward(N, I, Ng)
+/// (vXf32 (g_select
+/// (g_fcmp
+/// (g_intrinsic dot(vXf32 I) (vXf32 Ng)
+/// 0)
+/// (vXf32 N)
+/// (vXf32 g_fsub (0) (vXf32 N))))
+/// ->
+/// (vXf32 (g_intrinsic faceforward
+/// (vXf32 N) (vXf32 I) (vXf32 Ng)))
+///
+bool matchSelectToFaceForward(MachineInstr &MI, MachineRegisterInfo &MRI) {
+ if (MI.getOpcode() != TargetOpcode::G_SELECT)
----------------
kmpeng wrote:
Was trying to write this openCL test but ran into an issue of incorrect register types for `select`. I've filed an issue for it: #140590
https://github.com/llvm/llvm-project/pull/139959
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