[PATCH] D61374: AMDGPU: Don't clobber VCC in MUBUF addr64 emulation

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: rampitec, nhaehnle.
Herald added subscribers: t-tye, tpr, dstuttard, yaxunl, wdng, jvesely, kzhuravl.

Introducing VCC defs during SIFixSGPRCopies is generally
problematic. Avoid it by starting with the VOP3 form with the general
condition register. This is the easiest to fix instance, but doesn't
solve any specific problems I'm looking at.


https://reviews.llvm.org/D61374

Files:
  lib/Target/AMDGPU/SIInstrInfo.cpp
  test/CodeGen/AMDGPU/mubuf-legalize-operands.mir


Index: test/CodeGen/AMDGPU/mubuf-legalize-operands.mir
===================================================================
--- test/CodeGen/AMDGPU/mubuf-legalize-operands.mir
+++ test/CodeGen/AMDGPU/mubuf-legalize-operands.mir
@@ -147,15 +147,15 @@
 
 # COMMON-LABEL: name: addr64
 # COMMON-LABEL:  bb.0:
-# COMMON: %12:vreg_64 = COPY %8.sub0_sub1
-# COMMON: %13:sreg_64 = S_MOV_B64 0
-# COMMON: %14:sgpr_32 = S_MOV_B32 0
-# COMMON: %15:sgpr_32 = S_MOV_B32 61440
-# COMMON: %16:sreg_128 = REG_SEQUENCE %13, %subreg.sub0_sub1, %14, %subreg.sub2, %15, %subreg.sub3
-# COMMON: %9:vgpr_32 = V_ADD_I32_e32 %12.sub0, %4.sub0, implicit-def $vcc, implicit $exec
-# COMMON: %10:vgpr_32 = V_ADDC_U32_e32 %12.sub1, %4.sub1, implicit-def $vcc, implicit $vcc, implicit $exec
-# COMMON: %11:vreg_64 = REG_SEQUENCE %9, %subreg.sub0, %10, %subreg.sub1
-# COMMON: {{[0-9]+}}:vgpr_32 = BUFFER_LOAD_FORMAT_X_ADDR64 %11, killed %16, 0, 0, 0, 0, 0, implicit $exec
+# COMMON:  %14:vreg_64 = COPY %8.sub0_sub1
+# COMMON:  %15:sreg_64 = S_MOV_B64 0
+# COMMON:  %16:sgpr_32 = S_MOV_B32 0
+# COMMON:  %17:sgpr_32 = S_MOV_B32 61440
+# COMMON:  %18:sreg_128 = REG_SEQUENCE %15, %subreg.sub0_sub1, %16, %subreg.sub2, %17, %subreg.sub3
+# COMMON:  %9:vgpr_32, %12:sreg_64_xexec = V_ADD_I32_e64 %14.sub0, %4.sub0, 0, implicit $exec
+# COMMON:  %10:vgpr_32, dead %13:sreg_64_xexec = V_ADDC_U32_e64 %14.sub1, %4.sub1, killed %12, 0, implicit $exec
+# COMMON:  %11:vreg_64 = REG_SEQUENCE %9, %subreg.sub0, %10, %subreg.sub1
+# COMMON:  %{{[0-9]+}}:vgpr_32 = BUFFER_LOAD_FORMAT_X_ADDR64 %11, killed %18, 0, 0, 0, 0, 0, implicit $exec
 ---
 name:            addr64
 liveins:
Index: lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- lib/Target/AMDGPU/SIInstrInfo.cpp
+++ lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -4107,19 +4107,27 @@
       unsigned NewVAddrHi = MRI.createVirtualRegister(&AMDGPU::VGPR_32RegClass);
       unsigned NewVAddr = MRI.createVirtualRegister(&AMDGPU::VReg_64RegClass);
 
+      unsigned CondReg0 = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
+      unsigned CondReg1 = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
+
       unsigned RsrcPtr, NewSRsrc;
       std::tie(RsrcPtr, NewSRsrc) = extractRsrcPtr(*this, MI, *Rsrc);
 
       // NewVaddrLo = RsrcPtr:sub0 + VAddr:sub0
       DebugLoc DL = MI.getDebugLoc();
-      BuildMI(MBB, MI, DL, get(AMDGPU::V_ADD_I32_e32), NewVAddrLo)
-          .addReg(RsrcPtr, 0, AMDGPU::sub0)
-          .addReg(VAddr->getReg(), 0, AMDGPU::sub0);
+      BuildMI(MBB, MI, DL, get(AMDGPU::V_ADD_I32_e64), NewVAddrLo)
+        .addDef(CondReg0)
+        .addReg(RsrcPtr, 0, AMDGPU::sub0)
+        .addReg(VAddr->getReg(), 0, AMDGPU::sub0)
+        .addImm(0);
 
       // NewVaddrHi = RsrcPtr:sub1 + VAddr:sub1
-      BuildMI(MBB, MI, DL, get(AMDGPU::V_ADDC_U32_e32), NewVAddrHi)
-          .addReg(RsrcPtr, 0, AMDGPU::sub1)
-          .addReg(VAddr->getReg(), 0, AMDGPU::sub1);
+      BuildMI(MBB, MI, DL, get(AMDGPU::V_ADDC_U32_e64), NewVAddrHi)
+        .addDef(CondReg1, RegState::Dead)
+        .addReg(RsrcPtr, 0, AMDGPU::sub1)
+        .addReg(VAddr->getReg(), 0, AMDGPU::sub1)
+        .addReg(CondReg0, RegState::Kill)
+        .addImm(0);
 
       // NewVaddr = {NewVaddrHi, NewVaddrLo}
       BuildMI(MBB, MI, MI.getDebugLoc(), get(AMDGPU::REG_SEQUENCE), NewVAddr)


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