[llvm] [WIP][TableGen][GISel] Learn to import patterns with optional/physreg defs (PR #120343)

Sergei Barannikov via llvm-commits llvm-commits at lists.llvm.org
Tue Dec 17 17:37:24 PST 2024


https://github.com/s-barannikov updated https://github.com/llvm/llvm-project/pull/120343

>From 70dedcfce717d2e87ce2b9b8dd8732e487f3ebc8 Mon Sep 17 00:00:00 2001
From: Sergei Barannikov <barannikov88 at gmail.com>
Date: Tue, 17 Dec 2024 19:39:15 +0300
Subject: [PATCH] [TableGen][GISel] Learn to import patterns with
 optional/physreg defs

---
 .../Target/GlobalISel/SelectionDAGCompat.td   |   2 +
 .../test/CodeGen/X86/GlobalISel/mul-scalar.ll |   9 +-
 .../select-intrinsic-x86-flags-read-u32.mir   |   2 +-
 .../Common/GlobalISelEmitterCommon.td         |   3 +-
 .../GlobalISelEmitter-implicit-defs.td        |  62 ++++-
 .../GlobalISelEmitter-nested-subregs.td       |   2 +-
 .../TableGen/GlobalISelEmitterRegSequence.td  |   2 +-
 llvm/test/TableGen/GlobalISelEmitterSubreg.td |   8 +-
 .../TableGen/Common/CodeGenRegisters.cpp      |   2 +-
 llvm/utils/TableGen/Common/CodeGenRegisters.h |   2 +-
 .../GlobalISel/GlobalISelMatchTable.cpp       |   3 +-
 .../Common/GlobalISel/GlobalISelMatchTable.h  |   6 +-
 llvm/utils/TableGen/GlobalISelEmitter.cpp     | 236 +++++++++---------
 13 files changed, 195 insertions(+), 144 deletions(-)

diff --git a/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td b/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
index 2148f5be4c41aa..c8c0eeb57099a2 100644
--- a/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
+++ b/llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td
@@ -70,6 +70,8 @@ def : GINodeEquiv<G_SDIV, sdiv>;
 def : GINodeEquiv<G_UDIV, udiv>;
 def : GINodeEquiv<G_SREM, srem>;
 def : GINodeEquiv<G_UREM, urem>;
+def : GINodeEquiv<G_SDIVREM, sdivrem>;
+def : GINodeEquiv<G_UDIVREM, udivrem>;
 def : GINodeEquiv<G_AND, and>;
 def : GINodeEquiv<G_OR, or>;
 def : GINodeEquiv<G_XOR, xor>;
diff --git a/llvm/test/CodeGen/X86/GlobalISel/mul-scalar.ll b/llvm/test/CodeGen/X86/GlobalISel/mul-scalar.ll
index f401f45a06f6a7..3196668c70d8ec 100644
--- a/llvm/test/CodeGen/X86/GlobalISel/mul-scalar.ll
+++ b/llvm/test/CodeGen/X86/GlobalISel/mul-scalar.ll
@@ -5,16 +5,17 @@
 define i8 @test_mul_i8(i8 %arg1, i8 %arg2) nounwind {
 ; X64-LABEL: test_mul_i8:
 ; X64:       # %bb.0:
-; X64-NEXT:    movsbl %dil, %eax
-; X64-NEXT:    imulb %sil
+; X64-NEXT:    movl %edi, %eax
+; X64-NEXT:    # kill: def $al killed $al killed $eax
+; X64-NEXT:    mulb %sil
 ; X64-NEXT:    retq
 ;
 ; X86-LABEL: test_mul_i8:
 ; X86:       # %bb.0:
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
-; X86-NEXT:    cbtw
-; X86-NEXT:    imulb %cl
+; X86-NEXT:    # kill: def $al killed $al killed $eax
+; X86-NEXT:    mulb %cl
 ; X86-NEXT:    retl
   %ret = mul i8 %arg1, %arg2
   ret i8 %ret
diff --git a/llvm/test/CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir b/llvm/test/CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir
index 332ec2240c5b60..3d1857a274b4b2 100644
--- a/llvm/test/CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir
+++ b/llvm/test/CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir
@@ -9,7 +9,7 @@
   define void @read_flags() { ret void }
   ; CHECK-LABEL: name: read_flags
   ; CHECK: bb.0:
-  ; CHECK:   [[RDFLAGS32_:%[0-9]+]]:gr32 = RDFLAGS32 implicit-def $esp, implicit $esp
+  ; CHECK:   [[RDFLAGS32_:%[0-9]+]]:gr32 = RDFLAGS32 implicit-def dead $esp, implicit $esp
   ; CHECK:   $eax = COPY [[RDFLAGS32_]]
 ...
 
diff --git a/llvm/test/TableGen/Common/GlobalISelEmitterCommon.td b/llvm/test/TableGen/Common/GlobalISelEmitterCommon.td
index 8f11fee3751844..cfcaf3c76bbf8a 100644
--- a/llvm/test/TableGen/Common/GlobalISelEmitterCommon.td
+++ b/llvm/test/TableGen/Common/GlobalISelEmitterCommon.td
@@ -7,7 +7,8 @@ class MyTargetGenericInstruction : GenericInstruction {
 }
 
 def R0 : Register<"r0"> { let Namespace = "MyTarget"; }
-def GPR32 : RegisterClass<"MyTarget", [i32], 32, (add R0)>;
+def R1 : Register<"r0"> { let Namespace = "MyTarget"; }
+def GPR32 : RegisterClass<"MyTarget", [i32], 32, (add R0, R1)>;
 def GPR32Op : RegisterOperand<GPR32>;
 def F0 : Register<"f0"> { let Namespace = "MyTarget"; }
 def FPR32 : RegisterClass<"MyTarget", [f32], 32, (add F0)>;
diff --git a/llvm/test/TableGen/GlobalISelEmitter-implicit-defs.td b/llvm/test/TableGen/GlobalISelEmitter-implicit-defs.td
index 79af1a336f2890..ebf290a27b13ed 100644
--- a/llvm/test/TableGen/GlobalISelEmitter-implicit-defs.td
+++ b/llvm/test/TableGen/GlobalISelEmitter-implicit-defs.td
@@ -1,12 +1,60 @@
-// RUN: llvm-tblgen -gen-global-isel -warn-on-skipped-patterns -I %p/../../include -I %p/Common %s -o /dev/null 2>&1 < %s | FileCheck %s --implicit-check-not="Skipped pattern"
+// RUN: llvm-tblgen -gen-global-isel -I %p/../../include -I %p/Common %s | FileCheck %s
 
 include "llvm/Target/Target.td"
 include "GlobalISelEmitterCommon.td"
 
-// CHECK: Skipped pattern: Pattern defines a physical register
-let Uses = [B0], Defs = [B0] in
-def tst1 : I<(outs), (ins), [(set B0, (add B0, 1))]>;
+let Defs = [R0, R1] in
+def tst1 : I<(outs), (ins), [(set R0, (get_fpenv))]>;
 
-// CHECK: Skipped pattern: Src pattern result has 1 def(s) without the HasNoUse predicate set to true but Dst MI has no def
-let Uses = [B0] in
-def tst2 : I<(outs), (ins), [(set B0, (add B0, 1))]>;
+let Defs = [R0, R1] in
+def tst2 : I<(outs GPR32:$rd), (ins GPR32:$rs1, GPR32:$rs2),
+             [(set GPR32:$rd, R0, (udivrem i32:$rs1, i32:$rs2))]>;
+
+def : Pat<(sdiv i32:$rs1, i32:$rs2), (tst2 $rs1, $rs2)>;
+def : Pat<(sdivrem i32:$rs1, i32:$rs2), (tst2 $rs1, $rs2)>;
+
+// CHECK-LABEL: // (sdiv:{ *:[i32] } i32:{ *:[i32] }:$rs1, i32:{ *:[i32] }:$rs2)  =>  (tst2:{ *:[i32] }:{ *:[i32] } ?:{ *:[i32] }:$rs1, ?:{ *:[i32] }:$rs2)
+// CHECK-NEXT: GIR_MutateOpcode, /*InsnID*/0, /*RecycleInsnID*/0, /*Opcode*/GIMT_Encode2(MyTarget::tst2),
+// CHECK-NEXT: GIR_AddImplicitDef, /*InsnID*/0, GIMT_Encode2(MyTarget::R0), GIMT_Encode2(RegState::Dead),
+// CHECK-NEXT: GIR_AddImplicitDef, /*InsnID*/0, GIMT_Encode2(MyTarget::R1), GIMT_Encode2(RegState::Dead),
+// CHECK-NEXT: GIR_RootConstrainSelectedInstOperands,
+// CHECK-NEXT: // GIR_Coverage, 2,
+
+// CHECK-LABEL: // (sdivrem:{ *:[i32] }:{ *:[i32] } i32:{ *:[i32] }:$rs1, i32:{ *:[i32] }:$rs2)  =>  (tst2:{ *:[i32] }:{ *:[i32] } ?:{ *:[i32] }:$rs1, ?:{ *:[i32] }:$rs2)
+// CHECK-NEXT: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(MyTarget::tst2),
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/0, // DstI[rd]
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/2, // rs1
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/3, // rs2
+// CHECK-NEXT: GIR_SetImplicitDefDead, /*InsnID*/0, /*OpIdx for MyTarget::R1*/1,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/1, // DstI[R0]
+// CHECK-NEXT: GIR_AddRegister, /*InsnID*/1, GIMT_Encode2(MyTarget::R0), /*AddRegisterRegFlags*/GIMT_Encode2(0),
+// CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/1, /*Op*/0, GIMT_Encode2(MyTarget::GPR32RegClassID),
+// CHECK-NEXT: GIR_RootConstrainSelectedInstOperands,
+// CHECK-NEXT: // GIR_Coverage, 3,
+// CHECK-NEXT: GIR_EraseRootFromParent_Done,
+
+// CHECK-LABEL: // (udivrem:{ *:[i32] }:{ *:[i32] } i32:{ *:[i32] }:$rs1, i32:{ *:[i32] }:$rs2)  =>  (tst2:{ *:[i32] }:{ *:[i32] } i32:{ *:[i32] }:$rs1, i32:{ *:[i32] }:$rs2)
+// CHECK-NEXT: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(MyTarget::tst2),
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/0, // DstI[rd]
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/2, // rs1
+// CHECK-NEXT: GIR_RootToRootCopy, /*OpIdx*/3, // rs2
+// CHECK-NEXT: GIR_SetImplicitDefDead, /*InsnID*/0, /*OpIdx for MyTarget::R1*/1,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/1, // DstI[R0]
+// CHECK-NEXT: GIR_AddRegister, /*InsnID*/1, GIMT_Encode2(MyTarget::R0), /*AddRegisterRegFlags*/GIMT_Encode2(0),
+// CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/1, /*Op*/0, GIMT_Encode2(MyTarget::GPR32RegClassID),
+// CHECK-NEXT: GIR_RootConstrainSelectedInstOperands,
+// CHECK-NEXT: // GIR_Coverage, 1,
+// CHECK-NEXT: GIR_EraseRootFromParent_Done,
+
+// CHECK-LABEL: // (get_fpenv:{ *:[i32] })  =>  (tst1:{ *:[i32] })
+// CHECK-NEXT: GIR_BuildRootMI, /*Opcode*/GIMT_Encode2(MyTarget::tst1),
+// CHECK-NEXT: GIR_SetImplicitDefDead, /*InsnID*/0, /*OpIdx for MyTarget::R1*/1,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/0, // DstI[R0]
+// CHECK-NEXT: GIR_AddRegister, /*InsnID*/1, GIMT_Encode2(MyTarget::R0), /*AddRegisterRegFlags*/GIMT_Encode2(0),
+// CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/1, /*Op*/0, GIMT_Encode2(MyTarget::GPR32RegClassID),
+// CHECK-NEXT: GIR_RootConstrainSelectedInstOperands,
+// CHECK-NEXT: // GIR_Coverage, 0,
+// CHECK-NEXT: GIR_EraseRootFromParent_Done,
diff --git a/llvm/test/TableGen/GlobalISelEmitter-nested-subregs.td b/llvm/test/TableGen/GlobalISelEmitter-nested-subregs.td
index 1fdb973c1f1ec7..79e55ef2e8b8ce 100644
--- a/llvm/test/TableGen/GlobalISelEmitter-nested-subregs.td
+++ b/llvm/test/TableGen/GlobalISelEmitter-nested-subregs.td
@@ -38,11 +38,11 @@ def A0  : RegisterClass<"MyTarget", [i32], 32, (add a0)>;
 // CHECK-NEXT: // MIs[0] src
 // CHECK-NEXT: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s8,
 // CHECK-NEXT: // (anyext:{ *:[i16] } i8:{ *:[i8] }:$src)  =>  (EXTRACT_SUBREG:{ *:[i16] } (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), A0b:{ *:[i8] }:$src, lo8:{ *:[i32] }), lo16:{ *:[i32] })
-// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::INSERT_SUBREG),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_AddSimpleTempRegister, /*InsnID*/1, /*TempRegID*/1,
diff --git a/llvm/test/TableGen/GlobalISelEmitterRegSequence.td b/llvm/test/TableGen/GlobalISelEmitterRegSequence.td
index 3829070b28efeb..69f82eac49c161 100644
--- a/llvm/test/TableGen/GlobalISelEmitterRegSequence.td
+++ b/llvm/test/TableGen/GlobalISelEmitterRegSequence.td
@@ -39,12 +39,12 @@ def SUBSOME_INSN : I<(outs SRegs:$dst), (ins SOP:$src), []>;
 // CHECK-NEXT: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s16,
 // CHECK-NEXT: GIM_RootCheckRegBankForClass, /*Op*/1, /*RC*/GIMT_Encode2(Test::SRegsRegClassID),
 // CHECK-NEXT: // (sext:{ *:[i32] } SOP:{ *:[i16] }:$src)  =>  (REG_SEQUENCE:{ *:[i32] } DRegs:{ *:[i32] }, (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub0:{ *:[i32] }, (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub1:{ *:[i32] })
-// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
 // CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s16,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/0, /*OpIdx*/1, // src
 // CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/1, // src
diff --git a/llvm/test/TableGen/GlobalISelEmitterSubreg.td b/llvm/test/TableGen/GlobalISelEmitterSubreg.td
index 8df3238f6cc21e..08e690f3e894de 100644
--- a/llvm/test/TableGen/GlobalISelEmitterSubreg.td
+++ b/llvm/test/TableGen/GlobalISelEmitterSubreg.td
@@ -59,13 +59,13 @@ def : Pat<(sub (complex DOP:$src1, DOP:$src2), 77),
           (SOME_INSN2 (EXTRACT_SUBREG DOP:$src1, sub0),
                       (EXTRACT_SUBREG DOP:$src2, sub1))>;
 // CHECK-LABEL: // (sub:{ *:[i32] } (complex:{ *:[i32] } DOP:{ *:[i32] }:$src1, DOP:{ *:[i32] }:$src2), 77:{ *:[i32] })  =>  (SOME_INSN2:{ *:[i32] } (EXTRACT_SUBREG:{ *:[i32] } DOP:{ *:[i32] }:$src1, sub0:{ *:[i32] }), (EXTRACT_SUBREG:{ *:[i32] } DOP:{ *:[i32] }:$src2, sub1:{ *:[i32] }))
-// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_ComplexSubOperandSubRegRenderer, /*InsnID*/2, /*RendererID*/GIMT_Encode2(0), /*SubOperand*/1, /*SubRegIdx*/GIMT_Encode2(2), // src2
 // CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/2, /*Op*/0, GIMT_Encode2(Test::SRegsRegClassID),
 // CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/2, /*Op*/1, GIMT_Encode2(Test::DRegsRegClassID),
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_ComplexSubOperandSubRegRenderer, /*InsnID*/1, /*RendererID*/GIMT_Encode2(0), /*SubOperand*/0, /*SubRegIdx*/GIMT_Encode2(1), // src1
@@ -103,11 +103,11 @@ def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (IMPLICIT_DEF)), SOP:$src
 // instruction.
 def : Pat<(i32 (anyext i16:$src)), (SOME_INSN (INSERT_SUBREG (i32 (IMPLICIT_DEF)), SOP:$src, sub0))>;
 // CHECK-LABEL:  (anyext:{ *:[i32] } i16:{ *:[i16] }:$src)  =>  (SOME_INSN:{ *:[i32] } (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), SOP:{ *:[i16] }:$src, sub0:{ *:[i32] }))
-// CHECK-NEXT:            GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT:            GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
 // CHECK-NEXT:            GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
 // CHECK-NEXT:            GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT:            GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
+// CHECK-NEXT:            GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT:            GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::INSERT_SUBREG),
 // CHECK-NEXT:            GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT:            GIR_AddSimpleTempRegister, /*InsnID*/1, /*TempRegID*/1,
@@ -138,12 +138,12 @@ def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (COPY_TO_REGCLASS SOP:$sr
 // by a subinstruction.
 def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (IMPLICIT_DEF)), (SUBSOME_INSN SOP:$src), sub0)>;
 // CHECK-LABEL:  (anyext:{ *:[i32] } i16:{ *:[i16] }:$src)  =>  (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub0:{ *:[i32] })
-// CHECK-NEXT:          GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT:          GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s16,
 // CHECK-NEXT:          GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
 // CHECK-NEXT:          GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT:          GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/0, /*OpIdx*/1, // src
 // CHECK-NEXT:          GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
+// CHECK-NEXT:          GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
 // CHECK-NEXT:          GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
 // CHECK-NEXT:          GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT:          GIR_ConstrainSelectedInstOperands, /*InsnID*/1,
@@ -200,12 +200,12 @@ def : Pat<(i16 (trunc (bitreverse DOP:$src))),
 // CHECK-NEXT: GIM_CheckRegBankForClass, /*MI*/1, /*Op*/1, /*RC*/GIMT_Encode2(Test::DRegsRegClassID),
 // CHECK-NEXT: GIM_CheckIsSafeToFold, /*NumInsns*/1,
 // CHECK-NEXT: // (trunc:{ *:[i16] } (ctpop:{ *:[i32] } DOP:{ *:[i32] }:$src))  =>  (SUBSOME_INSN2:{ *:[i16] } (EXTRACT_SUBREG:{ *:[i16] } (SOME_INSN:{ *:[i32] } DOP:{ *:[i32] }:$src), sub0:{ *:[i32] }))
-// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
 // CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SOME_INSN),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/1, /*OpIdx*/1, // src
 // CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
 // CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
 // CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
 // CHECK-NEXT: GIR_AddTempSubRegister, /*InsnID*/1, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(0), GIMT_Encode2(sub0),
diff --git a/llvm/utils/TableGen/Common/CodeGenRegisters.cpp b/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
index 2dbee94d7e5406..011d11184c70c7 100644
--- a/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
+++ b/llvm/utils/TableGen/Common/CodeGenRegisters.cpp
@@ -2494,7 +2494,7 @@ CodeGenRegBank::getRegClassForRegister(const Record *R) {
 
 const CodeGenRegisterClass *
 CodeGenRegBank::getMinimalPhysRegClass(const Record *RegRecord,
-                                       ValueTypeByHwMode *VT) {
+                                       const ValueTypeByHwMode *VT) {
   const CodeGenRegister *Reg = getReg(RegRecord);
   const CodeGenRegisterClass *BestRC = nullptr;
   for (const auto &RC : getRegClasses()) {
diff --git a/llvm/utils/TableGen/Common/CodeGenRegisters.h b/llvm/utils/TableGen/Common/CodeGenRegisters.h
index 2fa6cab2afb892..90489cae6164ba 100644
--- a/llvm/utils/TableGen/Common/CodeGenRegisters.h
+++ b/llvm/utils/TableGen/Common/CodeGenRegisters.h
@@ -792,7 +792,7 @@ class CodeGenRegBank {
   // with a matching type
   const CodeGenRegisterClass *
   getMinimalPhysRegClass(const Record *RegRecord,
-                         ValueTypeByHwMode *VT = nullptr);
+                         const ValueTypeByHwMode *VT = nullptr);
 
   // Get the sum of unit weights.
   unsigned getRegUnitSetWeight(const std::vector<unsigned> &Units) const {
diff --git a/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.cpp b/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.cpp
index 15ec7e17130de4..6039211bc6cf00 100644
--- a/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.cpp
+++ b/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.cpp
@@ -1994,7 +1994,8 @@ void AddRegisterRenderer::emitRenderOpcodes(MatchTable &Table,
   // really needed for a physical register reference. We can pack the
   // register and flags in a single field.
   if (IsDef)
-    Table << MatchTable::NamedValue(2, "RegState::Define");
+    Table << MatchTable::NamedValue(
+        2, IsDead ? "RegState::Define | RegState::Dead" : "RegState::Define");
   else
     Table << MatchTable::IntValue(2, 0);
   Table << MatchTable::LineBreak;
diff --git a/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h b/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h
index 00fe073057c5c9..48ce71be677c08 100644
--- a/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h
+++ b/llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h
@@ -2091,13 +2091,15 @@ class AddRegisterRenderer : public OperandRenderer {
   unsigned InsnID;
   const Record *RegisterDef;
   bool IsDef;
+  bool IsDead;
   const CodeGenTarget &Target;
 
 public:
   AddRegisterRenderer(unsigned InsnID, const CodeGenTarget &Target,
-                      const Record *RegisterDef, bool IsDef = false)
+                      const Record *RegisterDef, bool IsDef = false,
+                      bool IsDead = false)
       : OperandRenderer(OR_Register), InsnID(InsnID), RegisterDef(RegisterDef),
-        IsDef(IsDef), Target(Target) {}
+        IsDef(IsDef), IsDead(IsDead), Target(Target) {}
 
   static bool classof(const OperandRenderer *R) {
     return R->getKind() == OR_Register;
diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
index 83599e789e10b9..9ac397548f0b9b 100644
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -324,8 +324,6 @@ class GlobalISelEmitter final : public GlobalISelMatchTableExecutorEmitter {
   void emitTestSimplePredicate(raw_ostream &OS) override;
   void emitRunCustomAction(raw_ostream &OS) override;
 
-  void postProcessRule(RuleMatcher &M);
-
   const CodeGenTarget &getTarget() const override { return Target; }
   StringRef getClassName() const override { return ClassName; }
 
@@ -384,44 +382,41 @@ class GlobalISelEmitter final : public GlobalISelMatchTableExecutorEmitter {
 
   Error importRulePredicates(RuleMatcher &M,
                              ArrayRef<const Record *> Predicates);
-  Expected<InstructionMatcher &>
-  createAndImportSelDAGMatcher(RuleMatcher &Rule,
-                               InstructionMatcher &InsnMatcher,
-                               const TreePatternNode &Src, unsigned &TempOpIdx);
+  Expected<InstructionMatcher &> createAndImportSelDAGMatcher(
+      RuleMatcher &Rule, InstructionMatcher &InsnMatcher,
+      const PatternToMatch &P, const TreePatternNode &Src, unsigned &TempOpIdx);
   Error importComplexPatternOperandMatcher(OperandMatcher &OM, const Record *R,
                                            unsigned &TempOpIdx) const;
   Error importChildMatcher(RuleMatcher &Rule, InstructionMatcher &InsnMatcher,
+                           const PatternToMatch &P,
                            const TreePatternNode &SrcChild,
                            bool OperandIsAPointer, bool OperandIsImmArg,
                            unsigned OpIdx, unsigned &TempOpIdx);
 
   Expected<BuildMIAction &> createAndImportInstructionRenderer(
-      RuleMatcher &M, InstructionMatcher &InsnMatcher,
+      RuleMatcher &M, InstructionMatcher &InsnMatcher, const PatternToMatch &P,
       const TreePatternNode &Src, const TreePatternNode &Dst);
   Expected<action_iterator> createAndImportSubInstructionRenderer(
-      action_iterator InsertPt, RuleMatcher &M, const TreePatternNode &Dst,
-      const TreePatternNode &Src, unsigned TempReg);
+      action_iterator InsertPt, RuleMatcher &M, const PatternToMatch &P,
+      const TreePatternNode &Dst, unsigned TempReg);
   Expected<action_iterator>
   createInstructionRenderer(action_iterator InsertPt, RuleMatcher &M,
                             const TreePatternNode &Dst);
 
   Expected<action_iterator>
-  importExplicitDefRenderers(action_iterator InsertPt, RuleMatcher &M,
-                             BuildMIAction &DstMIBuilder,
-                             const TreePatternNode &Src,
-                             const TreePatternNode &Dst, unsigned Start = 0);
+  importDefRenderers(action_iterator InsertPt, RuleMatcher &M,
+                     BuildMIAction &DstMIBuilder, const PatternToMatch &P,
+                     const TreePatternNode &Dst, unsigned Start = 0);
 
   Expected<action_iterator> importExplicitUseRenderers(
       action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-      const llvm::TreePatternNode &Dst, const TreePatternNode &Src);
+      const PatternToMatch &P, const TreePatternNode &Dst);
   Expected<action_iterator> importExplicitUseRenderer(
       action_iterator InsertPt, RuleMatcher &Rule, BuildMIAction &DstMIBuilder,
-      const TreePatternNode &DstChild, const TreePatternNode &Src);
+      const PatternToMatch &P, const TreePatternNode &DstChild);
   Error importDefaultOperandRenderers(action_iterator InsertPt, RuleMatcher &M,
                                       BuildMIAction &DstMIBuilder,
                                       const DAGDefaultOperand &DefaultOp) const;
-  Error importImplicitDefRenderers(BuildMIAction &DstMIBuilder,
-                                   ArrayRef<const Record *> ImplicitDefs) const;
 
   /// Analyze pattern \p P, returning a matcher for it if possible.
   /// Otherwise, return an Error explaining why we don't support it.
@@ -725,7 +720,7 @@ Expected<InstructionMatcher &> GlobalISelEmitter::addBuiltinPredicates(
 }
 
 Expected<InstructionMatcher &> GlobalISelEmitter::createAndImportSelDAGMatcher(
-    RuleMatcher &Rule, InstructionMatcher &InsnMatcher,
+    RuleMatcher &Rule, InstructionMatcher &InsnMatcher, const PatternToMatch &P,
     const TreePatternNode &Src, unsigned &TempOpIdx) {
   const auto SavedFlags = Rule.setGISelFlags(Src.getGISelFlagsRecord());
 
@@ -925,9 +920,9 @@ Expected<InstructionMatcher &> GlobalISelEmitter::createAndImportSelDAGMatcher(
         OperandIsImmArg |= II->isParamImmArg(I - 1);
       }
 
-      if (auto Error =
-              importChildMatcher(Rule, InsnMatcher, SrcChild, OperandIsAPointer,
-                                 OperandIsImmArg, OpIdx++, TempOpIdx))
+      if (auto Error = importChildMatcher(Rule, InsnMatcher, P, SrcChild,
+                                          OperandIsAPointer, OperandIsImmArg,
+                                          OpIdx++, TempOpIdx))
         return std::move(Error);
     }
   }
@@ -966,7 +961,7 @@ static StringRef getSrcChildName(const TreePatternNode &SrcChild,
 }
 
 Error GlobalISelEmitter::importChildMatcher(
-    RuleMatcher &Rule, InstructionMatcher &InsnMatcher,
+    RuleMatcher &Rule, InstructionMatcher &InsnMatcher, const PatternToMatch &P,
     const TreePatternNode &SrcChild, bool OperandIsAPointer,
     bool OperandIsImmArg, unsigned OpIdx, unsigned &TempOpIdx) {
 
@@ -1087,7 +1082,7 @@ Error GlobalISelEmitter::importChildMatcher(
     // Map the node to a gMIR instruction.
     InstructionOperandMatcher &InsnOperand = **MaybeInsnOperand;
     auto InsnMatcherOrError = createAndImportSelDAGMatcher(
-        Rule, InsnOperand.getInsnMatcher(), SrcChild, TempOpIdx);
+        Rule, InsnOperand.getInsnMatcher(), P, SrcChild, TempOpIdx);
     if (auto Error = InsnMatcherOrError.takeError())
       return Error;
 
@@ -1178,8 +1173,8 @@ Error GlobalISelEmitter::importChildMatcher(
       // has to succeed.
       OperandMatcher &OM =
           InsnOperand.getInsnMatcher().addOperand(0, "", TempOpIdx);
-      if (auto Error =
-              OM.addTypeCheckPredicate(TypeSetByHwMode(VTy), false /* OperandIsAPointer */))
+      if (auto Error = OM.addTypeCheckPredicate(TypeSetByHwMode(VTy),
+                                                false /* OperandIsAPointer */))
         return failedImport(toString(std::move(Error)) +
                             " for result of Src pattern operator");
 
@@ -1198,7 +1193,7 @@ Error GlobalISelEmitter::importChildMatcher(
 
 Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
     action_iterator InsertPt, RuleMatcher &Rule, BuildMIAction &DstMIBuilder,
-    const TreePatternNode &DstChild, const TreePatternNode &Src) {
+    const PatternToMatch &P, const TreePatternNode &DstChild) {
 
   const auto &SubOperand = Rule.getComplexSubOperand(DstChild.getName());
   if (SubOperand) {
@@ -1274,7 +1269,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
       DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID);
 
       auto InsertPtOrError = createAndImportSubInstructionRenderer(
-          ++InsertPt, Rule, DstChild, Src, TempRegID);
+          ++InsertPt, Rule, P, DstChild, TempRegID);
       if (auto Error = InsertPtOrError.takeError())
         return std::move(Error);
       return InsertPtOrError.get();
@@ -1362,8 +1357,8 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
 }
 
 Expected<BuildMIAction &> GlobalISelEmitter::createAndImportInstructionRenderer(
-    RuleMatcher &M, InstructionMatcher &InsnMatcher, const TreePatternNode &Src,
-    const TreePatternNode &Dst) {
+    RuleMatcher &M, InstructionMatcher &InsnMatcher, const PatternToMatch &P,
+    const TreePatternNode &Src, const TreePatternNode &Dst) {
   auto InsertPtOrError = createInstructionRenderer(M.actions_end(), M, Dst);
   if (auto Error = InsertPtOrError.takeError())
     return std::move(Error);
@@ -1383,13 +1378,11 @@ Expected<BuildMIAction &> GlobalISelEmitter::createAndImportInstructionRenderer(
   }
 
   if (auto Error =
-          importExplicitDefRenderers(InsertPt, M, DstMIBuilder, Src, Dst)
-              .takeError())
+          importDefRenderers(InsertPt, M, DstMIBuilder, P, Dst).takeError())
     return std::move(Error);
 
-  if (auto Error =
-          importExplicitUseRenderers(InsertPt, M, DstMIBuilder, Dst, Src)
-              .takeError())
+  if (auto Error = importExplicitUseRenderers(InsertPt, M, DstMIBuilder, P, Dst)
+                       .takeError())
     return std::move(Error);
 
   return DstMIBuilder;
@@ -1397,8 +1390,8 @@ Expected<BuildMIAction &> GlobalISelEmitter::createAndImportInstructionRenderer(
 
 Expected<action_iterator>
 GlobalISelEmitter::createAndImportSubInstructionRenderer(
-    const action_iterator InsertPt, RuleMatcher &M, const TreePatternNode &Dst,
-    const TreePatternNode &Src, unsigned TempRegID) {
+    const action_iterator InsertPt, RuleMatcher &M, const PatternToMatch &P,
+    const TreePatternNode &Dst, unsigned TempRegID) {
   auto InsertPtOrError = createInstructionRenderer(InsertPt, M, Dst);
 
   // TODO: Assert there's exactly one result.
@@ -1413,15 +1406,13 @@ GlobalISelEmitter::createAndImportSubInstructionRenderer(
   DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID, true);
 
   // Handle additional (ignored) results.
-  if (DstMIBuilder.getCGI()->Operands.NumDefs > 1) {
-    InsertPtOrError = importExplicitDefRenderers(
-        std::prev(*InsertPtOrError), M, DstMIBuilder, Src, Dst, /*Start=*/1);
-    if (auto Error = InsertPtOrError.takeError())
-      return std::move(Error);
-  }
+  InsertPtOrError = importDefRenderers(std::prev(*InsertPtOrError), M,
+                                       DstMIBuilder, P, Dst, /*Start=*/1);
+  if (auto Error = InsertPtOrError.takeError())
+    return std::move(Error);
 
   InsertPtOrError = importExplicitUseRenderers(InsertPtOrError.get(), M,
-                                               DstMIBuilder, Dst, Src);
+                                               DstMIBuilder, P, Dst);
   if (auto Error = InsertPtOrError.takeError())
     return std::move(Error);
 
@@ -1453,29 +1444,39 @@ Expected<action_iterator> GlobalISelEmitter::createInstructionRenderer(
                                        DstI);
 }
 
-Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
+Expected<action_iterator> GlobalISelEmitter::importDefRenderers(
     action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-    const TreePatternNode &Src, const TreePatternNode &Dst, unsigned Start) {
+    const PatternToMatch &P, const TreePatternNode &Dst, unsigned Start) {
   const CodeGenInstruction *DstI = DstMIBuilder.getCGI();
-  const unsigned SrcNumDefs = Src.getExtTypes().size();
-  const unsigned DstNumDefs = DstI->Operands.NumDefs;
-  if (DstNumDefs == 0)
-    return InsertPt;
-
-  for (unsigned I = Start; I < SrcNumDefs; ++I) {
-    std::string OpName = getMangledRootDefName(DstI->Operands[I].Name);
-    // CopyRenderer saves a StringRef, so cannot pass OpName itself -
-    // let's use a string with an appropriate lifetime.
-    StringRef PermanentRef = M.getOperandMatcher(OpName).getSymbolicName();
-    DstMIBuilder.addRenderer<CopyRenderer>(PermanentRef);
-  }
+  const unsigned DstExpDefs = DstI->Operands.NumDefs;
+  const unsigned DstNumDefs = DstExpDefs + DstI->ImplicitDefs.size();
+  bool IsRoot = &Dst == &P.getDstPattern();
+
+  unsigned I = Start;
+  for (; I < DstExpDefs; ++I) {
+    const CGIOperandList::OperandInfo &OpInfo = DstI->Operands[I];
+    std::string OpName = getMangledRootDefName(OpInfo.Name);
+
+    if (M.hasOperand(OpName)) {
+      // CopyRenderer saves a StringRef, so cannot pass OpName itself -
+      // let's use a string with an appropriate lifetime.
+      StringRef PermanentRef = M.getOperandMatcher(OpName).getSymbolicName();
+      DstMIBuilder.addRenderer<CopyRenderer>(PermanentRef);
+      continue;
+    }
 
-  // Some instructions have multiple defs, but are missing a type entry
-  // (e.g. s_cc_out operands).
-  if (Dst.getExtTypes().size() < DstNumDefs)
-    return failedImport("unhandled discarded def");
+    if (OpInfo.Rec->isSubClassOf("OptionalDefOperand")) {
+      const DAGDefaultOperand &ComplexOp = CGP.getDefaultOperand(OpInfo.Rec);
+      for (const TreePatternNode &SubOp :
+           make_pointee_range(ComplexOp.DefaultOps)) {
+        const Record *Reg = cast<DefInit>(SubOp.getLeafValue())->getDef();
+        assert(Reg->isSubClassOf("Register"));
+        DstMIBuilder.addRenderer<AddRegisterRenderer>(
+            Target, Reg, /*IsDef=*/true, /*IsDead=*/true);
+      }
+      continue;
+    }
 
-  for (unsigned I = SrcNumDefs; I < DstNumDefs; ++I) {
     const TypeSetByHwMode &ExtTy = Dst.getExtType(I);
     if (!ExtTy.isMachineValueType())
       return failedImport("unsupported typeset");
@@ -1487,7 +1488,30 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
     unsigned TempRegID = M.allocateTempRegID();
     InsertPt =
         M.insertAction<MakeTempRegisterAction>(InsertPt, *OpTy, TempRegID);
-    DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID, true, nullptr, true);
+    DstMIBuilder.addRenderer<TempRegRenderer>(
+        TempRegID, /*IsDef=*/true, /*SubReg=*/nullptr, /*IsDead=*/true);
+  }
+
+  for (; I < DstNumDefs; ++I) {
+    const Record *Reg = DstI->ImplicitDefs[I - DstExpDefs];
+    std::string OpName = getMangledRootDefName(Reg->getName());
+
+    if (!IsRoot || !M.hasOperand(OpName)) {
+      DstMIBuilder.setDeadImplicitDef(Reg);
+      continue;
+    }
+
+    BuildMIAction &CopyBuilder = M.addAction<BuildMIAction>(
+        M.allocateOutputInsnID(), &Target.getInstruction(RK.getDef("COPY")));
+
+    StringRef PermanentRef = M.getOperandMatcher(OpName).getSymbolicName();
+    CopyBuilder.addRenderer<CopyRenderer>(PermanentRef);
+    CopyBuilder.addRenderer<AddRegisterRenderer>(Target, Reg);
+
+    const CodeGenRegisterClass *RC = CGRegs.getRegClassForRegister(Reg);
+    assert(RC);
+    M.addAction<ConstrainOperandToRegClassAction>(CopyBuilder.getInsnID(),
+                                                  /*OpIdx=*/0, *RC);
   }
 
   return InsertPt;
@@ -1495,7 +1519,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
 
 Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
     action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-    const llvm::TreePatternNode &Dst, const llvm::TreePatternNode &Src) {
+    const PatternToMatch &P, const TreePatternNode &Dst) {
   const CodeGenInstruction *DstI = DstMIBuilder.getCGI();
   CodeGenInstruction *OrigDstI = &Target.getInstruction(Dst.getOperator());
 
@@ -1525,7 +1549,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
                                                         TempRegID);
 
       auto InsertPtOrError = createAndImportSubInstructionRenderer(
-          ++InsertPt, M, ValChild, Src, TempRegID);
+          ++InsertPt, M, P, ValChild, TempRegID);
       if (auto Error = InsertPtOrError.takeError())
         return std::move(Error);
 
@@ -1583,7 +1607,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
         CodeGenSubRegIndex *SubIdx = CGRegs.getSubRegIdx(SubRegInit->getDef());
 
         auto InsertPtOrError =
-            importExplicitUseRenderer(InsertPt, M, DstMIBuilder, ValChild, Src);
+            importExplicitUseRenderer(InsertPt, M, DstMIBuilder, P, ValChild);
         if (auto Error = InsertPtOrError.takeError())
           return std::move(Error);
         InsertPt = InsertPtOrError.get();
@@ -1652,7 +1676,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
     }
 
     auto InsertPtOrError = importExplicitUseRenderer(InsertPt, M, DstMIBuilder,
-                                                     Dst.getChild(Child), Src);
+                                                     P, Dst.getChild(Child));
     if (auto Error = InsertPtOrError.takeError())
       return std::move(Error);
     InsertPt = InsertPtOrError.get();
@@ -1710,13 +1734,6 @@ Error GlobalISelEmitter::importDefaultOperandRenderers(
   return Error::success();
 }
 
-Error GlobalISelEmitter::importImplicitDefRenderers(
-    BuildMIAction &DstMIBuilder, ArrayRef<const Record *> ImplicitDefs) const {
-  if (!ImplicitDefs.empty())
-    return failedImport("Pattern defines a physical register");
-  return Error::success();
-}
-
 Error GlobalISelEmitter::constrainOperands(action_iterator InsertPt,
                                            RuleMatcher &M, unsigned InsnID,
                                            const TreePatternNode &Dst) {
@@ -2042,7 +2059,7 @@ Expected<RuleMatcher> GlobalISelEmitter::runOnPattern(const PatternToMatch &P) {
   const auto SavedFlags = M.setGISelFlags(P.getSrcRecord());
 
   auto InsnMatcherOrError =
-      createAndImportSelDAGMatcher(M, InsnMatcherTemp, Src, TempOpIdx);
+      createAndImportSelDAGMatcher(M, InsnMatcherTemp, P, Src, TempOpIdx);
   if (auto Error = InsnMatcherOrError.takeError())
     return std::move(Error);
   InstructionMatcher &InsnMatcher = InsnMatcherOrError.get();
@@ -2093,13 +2110,14 @@ Expected<RuleMatcher> GlobalISelEmitter::runOnPattern(const PatternToMatch &P) {
   unsigned DstExpDefs = DstI.Operands.NumDefs,
            DstNumDefs = DstI.ImplicitDefs.size() + DstExpDefs,
            SrcNumDefs = Src.getExtTypes().size();
+
+  bool FoundNoUsePred = false;
   if (DstNumDefs < SrcNumDefs) {
     if (DstNumDefs != 0)
       return failedImport("Src pattern result has more defs than dst MI (" +
                           to_string(SrcNumDefs) + " def(s) vs " +
                           to_string(DstNumDefs) + " def(s))");
 
-    bool FoundNoUsePred = false;
     for (const auto &Pred : InsnMatcher.predicates()) {
       if ((FoundNoUsePred = isa<NoUsePredicateMatcher>(Pred.get())))
         break;
@@ -2112,15 +2130,24 @@ Expected<RuleMatcher> GlobalISelEmitter::runOnPattern(const PatternToMatch &P) {
 
   // The root of the match also has constraints on the register bank so that it
   // matches the result instruction.
-  unsigned N = std::min(DstExpDefs, SrcNumDefs);
-  for (unsigned I = 0; I < N; ++I) {
-    const auto &DstIOperand = DstI.Operands[I];
+  for (unsigned I = 0; I < SrcNumDefs; ++I) {
+    if (FoundNoUsePred)
+      continue;
 
     OperandMatcher &OM = InsnMatcher.getOperand(I);
+
+    if (I >= DstExpDefs) {
+      const Record *Reg = DstI.ImplicitDefs[I - DstExpDefs];
+      OM.setSymbolicName(getMangledRootDefName(Reg->getName()));
+      M.defineOperand(OM.getSymbolicName(), OM);
+      continue;
+    }
+
     // The operand names declared in the DstI instruction are unrelated to
     // those used in pattern's source and destination DAGs, so mangle the
     // former to prevent implicitly adding unexpected
     // GIM_CheckIsSameOperand predicates by the defineOperand method.
+    const CGIOperandList::OperandInfo &DstIOperand = DstI.Operands[I];
     OM.setSymbolicName(getMangledRootDefName(DstIOperand.Name));
     M.defineOperand(OM.getSymbolicName(), OM);
 
@@ -2133,16 +2160,11 @@ Expected<RuleMatcher> GlobalISelEmitter::runOnPattern(const PatternToMatch &P) {
   }
 
   auto DstMIBuilderOrError =
-      createAndImportInstructionRenderer(M, InsnMatcher, Src, Dst);
+      createAndImportInstructionRenderer(M, InsnMatcher, P, Src, Dst);
   if (auto Error = DstMIBuilderOrError.takeError())
     return std::move(Error);
   BuildMIAction &DstMIBuilder = DstMIBuilderOrError.get();
 
-  // Render the implicit defs.
-  // These are only added to the root of the result.
-  if (auto Error = importImplicitDefRenderers(DstMIBuilder, P.getDstRegs()))
-    return std::move(Error);
-
   DstMIBuilder.chooseInsnToMutate(M);
 
   // Constrain the registers to classes. This is normally derived from the
@@ -2179,15 +2201,15 @@ GlobalISelEmitter::buildMatchTable(MutableArrayRef<RuleMatcher> Rules,
       OpcodeOrder[Opcode] = CurrentOrdering++;
   }
 
-  llvm::stable_sort(InputRules, [&OpcodeOrder](const Matcher *A,
-                                               const Matcher *B) {
-    auto *L = static_cast<const RuleMatcher *>(A);
-    auto *R = static_cast<const RuleMatcher *>(B);
-    return std::tuple(OpcodeOrder[L->getOpcode()],
-                      L->insnmatchers_front().getNumOperandMatchers()) <
-           std::tuple(OpcodeOrder[R->getOpcode()],
-                      R->insnmatchers_front().getNumOperandMatchers());
-  });
+  llvm::stable_sort(
+      InputRules, [&OpcodeOrder](const Matcher *A, const Matcher *B) {
+        auto *L = static_cast<const RuleMatcher *>(A);
+        auto *R = static_cast<const RuleMatcher *>(B);
+        return std::tuple(OpcodeOrder[L->getOpcode()],
+                          L->insnmatchers_front().getNumOperandMatchers()) <
+               std::tuple(OpcodeOrder[R->getOpcode()],
+                          R->insnmatchers_front().getNumOperandMatchers());
+      });
 
   for (Matcher *Rule : InputRules)
     Rule->optimize();
@@ -2302,31 +2324,6 @@ void GlobalISelEmitter::emitRunCustomAction(raw_ostream &OS) {
      << "}\n";
 }
 
-void GlobalISelEmitter::postProcessRule(RuleMatcher &M) {
-  SmallPtrSet<const Record *, 16> UsedRegs;
-
-  // TODO: deal with subregs?
-  for (auto &A : M.actions()) {
-    auto *MI = dyn_cast<BuildMIAction>(A.get());
-    if (!MI)
-      continue;
-
-    for (auto *Use : MI->getCGI()->ImplicitUses)
-      UsedRegs.insert(Use);
-  }
-
-  for (auto &A : M.actions()) {
-    auto *MI = dyn_cast<BuildMIAction>(A.get());
-    if (!MI)
-      continue;
-
-    for (auto *Def : MI->getCGI()->ImplicitDefs) {
-      if (!UsedRegs.contains(Def))
-        MI->setDeadImplicitDef(Def);
-    }
-  }
-}
-
 void GlobalISelEmitter::run(raw_ostream &OS) {
   if (!UseCoverageFile.empty()) {
     RuleCoverage = CodeGenCoverage();
@@ -2386,7 +2383,6 @@ void GlobalISelEmitter::run(raw_ostream &OS) {
                      "Pattern is not covered by a test");
     }
     Rules.push_back(std::move(MatcherOrErr.get()));
-    postProcessRule(Rules.back());
   }
 
   // Comparison function to order records by name.



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