[llvm] gisel update (PR #128913)

[Brox Chen via llvm-commits]

https://github.com/broxigarchen updated https://github.com/llvm/llvm-project/pull/128913

>From 7b0ce276a47e458da9a6ab9b557d53b761bb8c1a Mon Sep 17 00:00:00 2001
From: guochen2 <guochen2 at amd.com>
Date: Wed, 26 Feb 2025 12:18:31 -0500
Subject: [PATCH] gisel update

---
 .../AMDGPU/AMDGPUInstructionSelector.cpp      | 26 +++++++++++++++----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
index a787c10a9421c..8a4ffa1c53931 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
@@ -639,7 +639,7 @@ bool AMDGPUInstructionSelector::selectG_MERGE_VALUES(MachineInstr &MI) const {
   LLT SrcTy = MRI->getType(MI.getOperand(1).getReg());
 
   const unsigned SrcSize = SrcTy.getSizeInBits();
-  if (SrcSize < 32)
+  if (SrcSize < 16)
     return selectImpl(MI, *CoverageInfo);
 
   const DebugLoc &DL = MI.getDebugLoc();
@@ -1478,10 +1478,17 @@ bool AMDGPUInstructionSelector::selectG_ICMP_or_FCMP(MachineInstr &I) const {
   if (Opcode == -1)
     return false;
 
-  MachineInstr *ICmp = BuildMI(*BB, &I, DL, TII.get(Opcode),
-            I.getOperand(0).getReg())
-            .add(I.getOperand(2))
-            .add(I.getOperand(3));
+  MachineInstrBuilder ICmp =
+      BuildMI(*BB, &I, DL, TII.get(Opcode), I.getOperand(0).getReg());
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::src0_modifiers))
+    ICmp.addImm(0);
+  ICmp.add(I.getOperand(2));
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::src1_modifiers))
+    ICmp.addImm(0);
+  ICmp.add(I.getOperand(3));
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::op_sel))
+    ICmp.addImm(0); // op_sel
+
   RBI.constrainGenericRegister(ICmp->getOperand(0).getReg(),
                                *TRI.getBoolRC(), *MRI);
   bool Ret = constrainSelectedInstRegOperands(*ICmp, TII, TRI, RBI);
@@ -4597,6 +4604,7 @@ AMDGPUInstructionSelector::selectVOP3OpSelMods(MachineOperand &Root) const {
   }};
 }
 
+// FIXME-TRUE16 remove when fake16 is removed
 InstructionSelector::ComplexRendererFns
 AMDGPUInstructionSelector::selectVINTERPMods(MachineOperand &Root) const {
   Register Src;
@@ -5841,6 +5849,14 @@ AMDGPUInstructionSelector::selectVOP3PMadMixModsImpl(MachineOperand &Root,
       CheckAbsNeg();
     }
 
+    // Since we looked through FPEXT and removed it, we must also remove
+    // G_TRUNC. G_TRUNC to 16-bits would have a destination in RC VGPR_16, which
+    // is not compatible with MadMix instructions
+    Register PeekSrc = Src;
+    if (Subtarget->useRealTrue16Insts() &&
+        mi_match(PeekSrc, *MRI, m_GTrunc(m_Reg(PeekSrc))))
+      Src = PeekSrc;
+
     Matched = true;
   }