[llvm] [TableGen][DecoderEmitter] Add option to emit type-specialized `decodeToMCInst` (PR #146593)

Rahul Joshi via llvm-commits llvm-commits at lists.llvm.org
Thu Jul 3 19:53:25 PDT 2025


https://github.com/jurahul updated https://github.com/llvm/llvm-project/pull/146593

>From ae24279533736da279301a884a926b906778bd21 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Tue, 1 Jul 2025 09:47:10 -0700
Subject: [PATCH 1/4] [TableGen][DecoderEmitter] Add option to emit
 type-specialized `decodeToMCInst`

---
 llvm/lib/Target/AArch64/CMakeLists.txt   |   3 +-
 llvm/lib/Target/AMDGPU/CMakeLists.txt    |   5 +-
 llvm/lib/Target/ARC/CMakeLists.txt       |   4 +-
 llvm/lib/Target/ARM/CMakeLists.txt       |   4 +-
 llvm/lib/Target/AVR/CMakeLists.txt       |   3 +-
 llvm/lib/Target/BPF/CMakeLists.txt       |   3 +-
 llvm/lib/Target/CSKY/CMakeLists.txt      |   3 +-
 llvm/lib/Target/Hexagon/CMakeLists.txt   |   3 +-
 llvm/lib/Target/Lanai/CMakeLists.txt     |   3 +-
 llvm/lib/Target/LoongArch/CMakeLists.txt |   3 +-
 llvm/lib/Target/MSP430/CMakeLists.txt    |   3 +-
 llvm/lib/Target/Mips/CMakeLists.txt      |   3 +-
 llvm/lib/Target/PowerPC/CMakeLists.txt   |   3 +-
 llvm/lib/Target/RISCV/CMakeLists.txt     |   4 +-
 llvm/lib/Target/Sparc/CMakeLists.txt     |   3 +-
 llvm/lib/Target/SystemZ/CMakeLists.txt   |   3 +-
 llvm/lib/Target/VE/CMakeLists.txt        |   3 +-
 llvm/lib/Target/XCore/CMakeLists.txt     |   4 +-
 llvm/lib/Target/Xtensa/CMakeLists.txt    |   3 +-
 llvm/test/TableGen/VarLenDecoder.td      |  13 +-
 llvm/utils/TableGen/DecoderEmitter.cpp   | 187 ++++++++++++++++++-----
 21 files changed, 202 insertions(+), 61 deletions(-)

diff --git a/llvm/lib/Target/AArch64/CMakeLists.txt b/llvm/lib/Target/AArch64/CMakeLists.txt
index 66136a464f05d..98cc8693144f0 100644
--- a/llvm/lib/Target/AArch64/CMakeLists.txt
+++ b/llvm/lib/Target/AArch64/CMakeLists.txt
@@ -7,7 +7,8 @@ tablegen(LLVM AArch64GenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AArch64GenAsmWriter1.inc -gen-asm-writer -asmwriternum=1)
 tablegen(LLVM AArch64GenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AArch64GenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AArch64GenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM AArch64GenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM AArch64GenFastISel.inc -gen-fast-isel)
 tablegen(LLVM AArch64GenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM AArch64GenO0PreLegalizeGICombiner.inc -gen-global-isel-combiner
diff --git a/llvm/lib/Target/AMDGPU/CMakeLists.txt b/llvm/lib/Target/AMDGPU/CMakeLists.txt
index e3519f192137c..6254750c10c3c 100644
--- a/llvm/lib/Target/AMDGPU/CMakeLists.txt
+++ b/llvm/lib/Target/AMDGPU/CMakeLists.txt
@@ -6,7 +6,10 @@ tablegen(LLVM AMDGPUGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM AMDGPUGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AMDGPUGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AMDGPUGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AMDGPUGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM AMDGPUGenDisassemblerTables.inc -gen-disassembler
+         -non-templated-decode-to-mcinst-type-spec=uint32_t:=32
+         -non-templated-decode-to-mcinst-type-spec=uint64_t:=64
+         -non-templated-decode-to-mcinst-type-spec=DecoderUInt128:=96,128)
 tablegen(LLVM AMDGPUGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM AMDGPUGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM AMDGPUGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/ARC/CMakeLists.txt b/llvm/lib/Target/ARC/CMakeLists.txt
index 196cc31cc5080..e6656576fbcc3 100644
--- a/llvm/lib/Target/ARC/CMakeLists.txt
+++ b/llvm/lib/Target/ARC/CMakeLists.txt
@@ -5,7 +5,9 @@ set(LLVM_TARGET_DEFINITIONS ARC.td)
 tablegen(LLVM ARCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM ARCGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM ARCGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM ARCGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM ARCGenDisassemblerTables.inc -gen-disassembler
+         -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32
+         -non-templated-decode-to-mcinst-type-spec=uint64_t:=48,64)
 tablegen(LLVM ARCGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM ARCGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM ARCGenSDNodeInfo.inc -gen-sd-node-info)
diff --git a/llvm/lib/Target/ARM/CMakeLists.txt b/llvm/lib/Target/ARM/CMakeLists.txt
index a39629bd8aeb0..718a084ec6388 100644
--- a/llvm/lib/Target/ARM/CMakeLists.txt
+++ b/llvm/lib/Target/ARM/CMakeLists.txt
@@ -6,7 +6,9 @@ tablegen(LLVM ARMGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM ARMGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM ARMGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM ARMGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM ARMGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM ARMGenDisassemblerTables.inc -gen-disassembler
+         -non-templated-decode-to-mcinst-type-spec=uint16_t:=16
+         -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM ARMGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM ARMGenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM ARMGenInstrInfo.inc -gen-instr-info)
diff --git a/llvm/lib/Target/AVR/CMakeLists.txt b/llvm/lib/Target/AVR/CMakeLists.txt
index 781dac02c7083..a2da85d77a325 100644
--- a/llvm/lib/Target/AVR/CMakeLists.txt
+++ b/llvm/lib/Target/AVR/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM AVRGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM AVRGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AVRGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AVRGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AVRGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM AVRGenDisassemblerTables.inc -gen-disassembler
+         -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
 tablegen(LLVM AVRGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM AVRGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM AVRGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/BPF/CMakeLists.txt b/llvm/lib/Target/BPF/CMakeLists.txt
index eade4cacb7100..6a609d645dfa1 100644
--- a/llvm/lib/Target/BPF/CMakeLists.txt
+++ b/llvm/lib/Target/BPF/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM BPFGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM BPFGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM BPFGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM BPFGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM BPFGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM BPFGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint64_t:=64)
 tablegen(LLVM BPFGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM BPFGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM BPFGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/CSKY/CMakeLists.txt b/llvm/lib/Target/CSKY/CMakeLists.txt
index 4b900bc99c271..eadf0169edef1 100644
--- a/llvm/lib/Target/CSKY/CMakeLists.txt
+++ b/llvm/lib/Target/CSKY/CMakeLists.txt
@@ -7,7 +7,8 @@ tablegen(LLVM CSKYGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM CSKYGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM CSKYGenCompressInstEmitter.inc -gen-compress-inst-emitter)
 tablegen(LLVM CSKYGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM CSKYGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM CSKYGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
 tablegen(LLVM CSKYGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM CSKYGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM CSKYGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/Hexagon/CMakeLists.txt b/llvm/lib/Target/Hexagon/CMakeLists.txt
index d758260a8ab5d..be2bc89155612 100644
--- a/llvm/lib/Target/Hexagon/CMakeLists.txt
+++ b/llvm/lib/Target/Hexagon/CMakeLists.txt
@@ -7,7 +7,8 @@ tablegen(LLVM HexagonGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM HexagonGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM HexagonGenDAGISel.inc -gen-dag-isel)
 tablegen(LLVM HexagonGenDFAPacketizer.inc -gen-dfa-packetizer)
-tablegen(LLVM HexagonGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM HexagonGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM HexagonGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM HexagonGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM HexagonGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/Lanai/CMakeLists.txt b/llvm/lib/Target/Lanai/CMakeLists.txt
index 4a628e13fc177..dfb0c93e1a5e3 100644
--- a/llvm/lib/Target/Lanai/CMakeLists.txt
+++ b/llvm/lib/Target/Lanai/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM LanaiGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM LanaiGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM LanaiGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM LanaiGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM LanaiGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM LanaiGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM LanaiGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM LanaiGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM LanaiGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/LoongArch/CMakeLists.txt b/llvm/lib/Target/LoongArch/CMakeLists.txt
index 0f674b1b0fa9e..c851f5c2fc1da 100644
--- a/llvm/lib/Target/LoongArch/CMakeLists.txt
+++ b/llvm/lib/Target/LoongArch/CMakeLists.txt
@@ -5,7 +5,8 @@ set(LLVM_TARGET_DEFINITIONS LoongArch.td)
 tablegen(LLVM LoongArchGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM LoongArchGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM LoongArchGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM LoongArchGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM LoongArchGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM LoongArchGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM LoongArchGenMCPseudoLowering.inc -gen-pseudo-lowering)
 tablegen(LLVM LoongArchGenMCCodeEmitter.inc -gen-emitter)
diff --git a/llvm/lib/Target/MSP430/CMakeLists.txt b/llvm/lib/Target/MSP430/CMakeLists.txt
index 4081d3472fd78..f10c8192e7df0 100644
--- a/llvm/lib/Target/MSP430/CMakeLists.txt
+++ b/llvm/lib/Target/MSP430/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM MSP430GenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM MSP430GenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM MSP430GenCallingConv.inc -gen-callingconv)
 tablegen(LLVM MSP430GenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM MSP430GenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM MSP430GenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,32,48)
 tablegen(LLVM MSP430GenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM MSP430GenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM MSP430GenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/Mips/CMakeLists.txt b/llvm/lib/Target/Mips/CMakeLists.txt
index 21d1765107ae6..2516d00706a91 100644
--- a/llvm/lib/Target/Mips/CMakeLists.txt
+++ b/llvm/lib/Target/Mips/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM MipsGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM MipsGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM MipsGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM MipsGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM MipsGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM MipsGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
 tablegen(LLVM MipsGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM MipsGenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM MipsGenPostLegalizeGICombiner.inc -gen-global-isel-combiner
diff --git a/llvm/lib/Target/PowerPC/CMakeLists.txt b/llvm/lib/Target/PowerPC/CMakeLists.txt
index 3808a26a0b92a..136db0634eb93 100644
--- a/llvm/lib/Target/PowerPC/CMakeLists.txt
+++ b/llvm/lib/Target/PowerPC/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM PPCGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM PPCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM PPCGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM PPCGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler
+               -non-templated-decode-to-mcinst-type-spec=uint64_t:=32,64)
 tablegen(LLVM PPCGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM PPCGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM PPCGenMCCodeEmitter.inc -gen-emitter)
diff --git a/llvm/lib/Target/RISCV/CMakeLists.txt b/llvm/lib/Target/RISCV/CMakeLists.txt
index e32d6eab3b977..9df6701387d43 100644
--- a/llvm/lib/Target/RISCV/CMakeLists.txt
+++ b/llvm/lib/Target/RISCV/CMakeLists.txt
@@ -7,7 +7,9 @@ tablegen(LLVM RISCVGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM RISCVGenCompressInstEmitter.inc -gen-compress-inst-emitter)
 tablegen(LLVM RISCVGenMacroFusion.inc -gen-macro-fusion-pred)
 tablegen(LLVM RISCVGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM RISCVGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM RISCVGenDisassemblerTables.inc -gen-disassembler
+              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32
+              -non-templated-decode-to-mcinst-type-spec=uint64_t:=48)
 tablegen(LLVM RISCVGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM RISCVGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM RISCVGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/Sparc/CMakeLists.txt b/llvm/lib/Target/Sparc/CMakeLists.txt
index f682719ac483f..6334dbbc6cc1a 100644
--- a/llvm/lib/Target/Sparc/CMakeLists.txt
+++ b/llvm/lib/Target/Sparc/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM SparcGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM SparcGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM SparcGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM SparcGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM SparcGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM SparcGenDisassemblerTables.inc -gen-disassembler
+               -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM SparcGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM SparcGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM SparcGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/SystemZ/CMakeLists.txt b/llvm/lib/Target/SystemZ/CMakeLists.txt
index 0d8f3eac6ee4f..1caeef468f3fb 100644
--- a/llvm/lib/Target/SystemZ/CMakeLists.txt
+++ b/llvm/lib/Target/SystemZ/CMakeLists.txt
@@ -7,7 +7,8 @@ tablegen(LLVM SystemZGenGNUAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM SystemZGenHLASMAsmWriter.inc -gen-asm-writer -asmwriternum=1)
 tablegen(LLVM SystemZGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM SystemZGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM SystemZGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM SystemZGenDisassemblerTables.inc -gen-disassembler
+               -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,32,48)
 tablegen(LLVM SystemZGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM SystemZGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM SystemZGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/VE/CMakeLists.txt b/llvm/lib/Target/VE/CMakeLists.txt
index d1bb4f32fcba7..6b83a3e7ae28e 100644
--- a/llvm/lib/Target/VE/CMakeLists.txt
+++ b/llvm/lib/Target/VE/CMakeLists.txt
@@ -4,7 +4,8 @@ set(LLVM_TARGET_DEFINITIONS VE.td)
 
 tablegen(LLVM VEGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM VEGenInstrInfo.inc -gen-instr-info)
-tablegen(LLVM VEGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM VEGenDisassemblerTables.inc -gen-disassembler
+               -non-templated-decode-to-mcinst-type-spec=uint64_t:=64)
 tablegen(LLVM VEGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM VEGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM VEGenAsmMatcher.inc -gen-asm-matcher)
diff --git a/llvm/lib/Target/XCore/CMakeLists.txt b/llvm/lib/Target/XCore/CMakeLists.txt
index f411c658b43b0..3b5bf848d8144 100644
--- a/llvm/lib/Target/XCore/CMakeLists.txt
+++ b/llvm/lib/Target/XCore/CMakeLists.txt
@@ -5,7 +5,9 @@ set(LLVM_TARGET_DEFINITIONS XCore.td)
 tablegen(LLVM XCoreGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM XCoreGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM XCoreGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM XCoreGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM XCoreGenDisassemblerTables.inc -gen-disassembler
+          -non-templated-decode-to-mcinst-type-spec=uint16_t:=16
+          -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
 tablegen(LLVM XCoreGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM XCoreGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM XCoreGenSDNodeInfo.inc -gen-sd-node-info)
diff --git a/llvm/lib/Target/Xtensa/CMakeLists.txt b/llvm/lib/Target/Xtensa/CMakeLists.txt
index 4fc1ba6dfa650..9c825b5d880c7 100644
--- a/llvm/lib/Target/Xtensa/CMakeLists.txt
+++ b/llvm/lib/Target/Xtensa/CMakeLists.txt
@@ -6,7 +6,8 @@ tablegen(LLVM XtensaGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM XtensaGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM XtensaGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM XtensaGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM XtensaGenDisassemblerTables.inc -gen-disassembler)
+tablegen(LLVM XtensaGenDisassemblerTables.inc -gen-disassembler
+               -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,24)
 tablegen(LLVM XtensaGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM XtensaGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM XtensaGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/test/TableGen/VarLenDecoder.td b/llvm/test/TableGen/VarLenDecoder.td
index 06ff62294a196..2359bd2c15145 100644
--- a/llvm/test/TableGen/VarLenDecoder.td
+++ b/llvm/test/TableGen/VarLenDecoder.td
@@ -61,11 +61,7 @@ def FOO32 : MyVarInst<MemOp32> {
 // CHECK-LARGE-NEXT: /* 14 */      MCD::OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 1, // Opcode: FOO32
 // CHECK-LARGE-NEXT: /* 18 */      MCD::OPC_Fail,
 
-// Instruction length table
-// CHECK: 27,
-// CHECK-NEXT: 43,
-// CHECK-NEXT: };
-
+// CHECK-LABEL: decodeToMCInst
 // CHECK:      case 0:
 // CHECK-NEXT: tmp = fieldFromInstruction(insn, 8, 3);
 // CHECK-NEXT: if (!Check(S, DecodeRegClassRegisterClass(MI, tmp, Address, Decoder))) { return MCDisassembler::Fail; }
@@ -85,6 +81,13 @@ def FOO32 : MyVarInst<MemOp32> {
 // CHECK-NEXT: MI.addOperand(MCOperand::createImm(tmp));
 // CHECK-NEXT: return S;
 
+// Instruction length table
+// CHECK-LABEL: InstrLenTable
+// CHECK: 27,
+// CHECK-NEXT: 43,
+// CHECK-NEXT: };
+
+// CHECK-LABEL: decodeInstruction
 // CHECK-LABEL: case MCD::OPC_ExtractField: {
 // CHECK: makeUp(insn, Start + Len);
 
diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index d582309a6fd4a..ae3f072601014 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -23,6 +23,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallBitVector.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringExtras.h"
@@ -92,6 +93,22 @@ static cl::opt<bool> UseFnTableInDecodeToMCInst(
         "of the generated code."),
     cl::init(false), cl::cat(DisassemblerEmitterCat));
 
+// Option to generate a non-templated version of `decodeToMCInst`. The
+// templated `decodeToMCInst` is templated on `InsnType` and a given `InsnType`
+// can target instructions with one or more Bitwidths. So the option to
+// generate a non-templated `decodeToMCInst` is a typespec of the form
+// type::=list-of-sizes.
+
+// For example, for the AMDGPU target, the type `DecoderUInt128` is used for
+// both 96 and 128 bit instructions. So the generated non-templated
+// `decodeToMCInst` will support decoding both these instruction Bitwidths and
+// the option will be DecoderUInt128::=96,128
+static cl::list<std::string> DecodeToMCInstTypeSpecs(
+    "non-templated-decode-to-mcinst-type-spec",
+    cl::desc("list of C++ types and associated bitwidths to used to generate "
+             "non-templated `decodeToMCInst`."),
+    cl::cat(DisassemblerEmitterCat));
+
 STATISTIC(NumEncodings, "Number of encodings considered");
 STATISTIC(NumEncodingsLackingDisasm,
           "Number of encodings without disassembler info");
@@ -234,7 +251,7 @@ class DecoderEmitter {
   void emitPredicateFunction(formatted_raw_ostream &OS,
                              PredicateSet &Predicates, indent Indent) const;
   void emitDecoderFunction(formatted_raw_ostream &OS, DecoderSet &Decoders,
-                           indent Indent) const;
+                           StringRef SpecializedInsnType, indent Indent) const;
 
   // run - Output the code emitter
   void run(raw_ostream &o);
@@ -1068,24 +1085,35 @@ void DecoderEmitter::emitPredicateFunction(formatted_raw_ostream &OS,
 
 void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
                                          DecoderSet &Decoders,
+                                         StringRef SpecializedInsnType,
                                          indent Indent) const {
+  auto emitTemplate = [&OS, SpecializedInsnType, &Indent] {
+    if (SpecializedInsnType.empty())
+      OS << Indent << "template <typename InsnType>\n";
+  };
+
+  StringRef InsnType =
+      SpecializedInsnType.empty() ? "InsnType" : SpecializedInsnType;
+
   // The decoder function is just a big switch statement or a table of function
   // pointers based on the input decoder index.
 
   // TODO: When InsnType is large, using uint64_t limits all fields to 64 bits
   // It would be better for emitBinaryParser to use a 64-bit tmp whenever
   // possible but fall back to an InsnType-sized tmp for truly large fields.
-  StringRef TmpTypeDecl =
-      "using TmpType = std::conditional_t<std::is_integral<InsnType>::value, "
-      "InsnType, uint64_t>;\n";
-  StringRef DecodeParams =
-      "DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const "
-      "MCDisassembler *Decoder, bool &DecodeComplete";
+  auto TmpTypeDecl = formatv(
+      "using TmpType = std::conditional_t<std::is_integral<{0}>::value, {0}, "
+      "uint64_t>;\n",
+      InsnType);
+  auto DecodeParams =
+      formatv("DecodeStatus S, {} insn, MCInst &MI, uint64_t Address, const "
+              "MCDisassembler *Decoder, bool &DecodeComplete",
+              InsnType);
 
   if (UseFnTableInDecodeToMCInst) {
     // Emit a function for each case first.
     for (const auto &[Index, Decoder] : enumerate(Decoders)) {
-      OS << Indent << "template <typename InsnType>\n";
+      emitTemplate();
       OS << Indent << "DecodeStatus decodeFn" << Index << "(" << DecodeParams
          << ") {\n";
       Indent += 2;
@@ -1099,7 +1127,7 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
   }
 
   OS << Indent << "// Handling " << Decoders.size() << " cases.\n";
-  OS << Indent << "template <typename InsnType>\n";
+  emitTemplate();
   OS << Indent << "static DecodeStatus decodeToMCInst(unsigned Idx, "
      << DecodeParams << ") {\n";
   Indent += 2;
@@ -2538,6 +2566,70 @@ handleHwModesUnrelatedEncodings(const CodeGenInstruction *Instr,
   }
 }
 
+// Result of parsing a single `non-templated-decode-to-mcinst-type-spec` option.
+using BitwidthSet = SmallSet<unsigned, 4>;
+struct NonTemplatedTypeSpec {
+  StringRef Type;
+  BitwidthSet Bitwidths;
+};
+
+static SmallVector<NonTemplatedTypeSpec>
+parseNonTemplatedTypeSpec(BitwidthSet &InstrBitwidths) {
+  SmallVector<NonTemplatedTypeSpec> Parsed;
+  if (DecodeToMCInstTypeSpecs.empty()) {
+    // If no `non-templated-decode-to-mcinst-type-spec` option is specified,
+    // create a type-spec with empty values, which will trigger generation of
+    // a templated `decodeToMCInst`.
+    Parsed.emplace_back();
+    return Parsed;
+  }
+
+  Parsed.reserve(DecodeToMCInstTypeSpecs.size());
+  BitwidthSet OptionBitwidths;
+
+  for (StringRef TypeSpec : DecodeToMCInstTypeSpecs) {
+    BitwidthSet Bitwidths;
+    // Each `non-templated-decode-to-mcinst-type-spec` is of the form
+    // <type>:=<list of bitwidths>. Note, <type> can in general be a templated
+    // type, so using the token ":=" as a separator to allow many general C++
+    // types here.
+    auto [Type, ListOfBitWidths] = TypeSpec.split(":=");
+    if (Type.empty())
+      PrintFatalError("Invalid typespec: " + TypeSpec);
+
+    for (StringRef BwStr : split(ListOfBitWidths, ',')) {
+      unsigned Bitwidth;
+      if (BwStr.getAsInteger(10, Bitwidth))
+        PrintFatalError("Invalid bitwidth: " + BwStr + " in typespec " +
+                        TypeSpec);
+
+      if (!OptionBitwidths.insert(Bitwidth).second)
+        PrintFatalError("Bitwidth " + Twine(Bitwidth) + " already specified.");
+
+      if (!InstrBitwidths.contains(Bitwidth))
+        PrintFatalError(Twine("No instruction of Bitwidth ") + Twine(Bitwidth) +
+                        " supported.");
+
+      InstrBitwidths.erase(Bitwidth);
+      Bitwidths.insert(Bitwidth);
+    }
+
+    if (Bitwidths.empty())
+      PrintFatalError("No bitwidth specified in typespec " + TypeSpec);
+
+    Parsed.emplace_back(NonTemplatedTypeSpec{Type, Bitwidths});
+  }
+
+  if (!InstrBitwidths.empty()) {
+    PrintFatalError([&InstrBitwidths](raw_ostream &OS) {
+      OS << "Bitwidth(s) ";
+      llvm::interleaveComma(InstrBitwidths, OS);
+      OS << " missing in `non-templated-decode-to-mcinst-type-spec` options.";
+    });
+  }
+  return Parsed;
+}
+
 // Emits disassembler code for instruction decoding.
 void DecoderEmitter::run(raw_ostream &o) {
   formatted_raw_ostream OS(o);
@@ -2649,35 +2741,59 @@ namespace {
     }
   }
 
+  // Collect all allowed Bitwidths for instructions.
+  BitwidthSet InstrBitwidths;
+  for (const auto &[NSAndByteSize, _] : OpcMap) {
+    const unsigned Bitwidth = 8 * NSAndByteSize.second;
+    InstrBitwidths.insert(Bitwidth);
+  }
+  SmallVector<NonTemplatedTypeSpec> NonTemplatedTypeSpecs =
+      parseNonTemplatedTypeSpec(InstrBitwidths);
+
   DecoderTableInfo TableInfo;
   unsigned OpcodeMask = 0;
-  for (const auto &[NSAndByteSize, EncodingIDs] : OpcMap) {
-    const std::string &DecoderNamespace = NSAndByteSize.first;
-    const unsigned BitWidth = 8 * NSAndByteSize.second;
-    // Emit the decoder for this namespace+width combination.
-    FilterChooser FC(NumberedEncodings, EncodingIDs, Operands,
-                     IsVarLenInst ? MaxInstLen : BitWidth, this);
-
-    // The decode table is cleared for each top level decoder function. The
-    // predicates and decoders themselves, however, are shared across all
-    // decoders to give more opportunities for uniqueing.
-    TableInfo.Table.clear();
-    TableInfo.FixupStack.clear();
-    TableInfo.FixupStack.emplace_back();
-    FC.emitTableEntries(TableInfo);
-    // Any NumToSkip fixups in the top level scope can resolve to the
-    // OPC_Fail at the end of the table.
-    assert(TableInfo.FixupStack.size() == 1 && "fixup stack phasing error!");
-    // Resolve any NumToSkip fixups in the current scope.
-    resolveTableFixups(TableInfo.Table, TableInfo.FixupStack.back(),
-                       TableInfo.Table.size());
-    TableInfo.FixupStack.clear();
+  for (const auto &[NTType, NTBitwidths] : NonTemplatedTypeSpecs) {
+    // Reset the Decoders for each non-templated type.
+    TableInfo.Decoders.clear();
+
+    for (const auto &[NSAndByteSize, EncodingIDs] : OpcMap) {
+      const std::string &DecoderNamespace = NSAndByteSize.first;
+      const unsigned InstrBitwidth =
+          IsVarLenInst ? MaxInstLen : 8 * NSAndByteSize.second;
+
+      // Only handle instruction of the non-templated bitwidth size when
+      // non-templated bitwidth option is enabled.
+      if (!NTBitwidths.empty() && !NTBitwidths.contains(InstrBitwidth))
+        continue;
+
+      // Emit the decoder for this namespace+width combination.
+      FilterChooser FC(NumberedEncodings, EncodingIDs, Operands,
+                       IsVarLenInst ? MaxInstLen : InstrBitwidth, this);
+
+      // The decode table is cleared for each top level decoder function. The
+      // predicates and decoders themselves, however, are shared across all
+      // decoders to give more opportunities for uniqueing.
+      TableInfo.Table.clear();
+      TableInfo.FixupStack.clear();
+      TableInfo.FixupStack.emplace_back();
+      FC.emitTableEntries(TableInfo);
+      // Any NumToSkip fixups in the top level scope can resolve to the
+      // OPC_Fail at the end of the table.
+      assert(TableInfo.FixupStack.size() == 1 && "fixup stack phasing error!");
+      // Resolve any NumToSkip fixups in the current scope.
+      resolveTableFixups(TableInfo.Table, TableInfo.FixupStack.back(),
+                         TableInfo.Table.size());
+      TableInfo.FixupStack.clear();
 
-    TableInfo.Table.push_back(MCD::OPC_Fail);
+      TableInfo.Table.push_back(MCD::OPC_Fail);
 
-    // Print the table to the output stream.
-    OpcodeMask |= emitTable(OS, TableInfo.Table, indent(0), FC.getBitWidth(),
-                            DecoderNamespace, EncodingIDs);
+      // Print the table to the output stream.
+      OpcodeMask |= emitTable(OS, TableInfo.Table, indent(0), FC.getBitWidth(),
+                              DecoderNamespace, EncodingIDs);
+    }
+
+    // Emit the decoder function for this BitWidth.
+    emitDecoderFunction(OS, TableInfo.Decoders, NTType, indent(0));
   }
 
   // For variable instruction, we emit a instruction length table
@@ -2694,9 +2810,6 @@ namespace {
   if (HasCheckPredicate)
     emitPredicateFunction(OS, TableInfo.Predicates, indent(0));
 
-  // Emit the decoder function.
-  emitDecoderFunction(OS, TableInfo.Decoders, indent(0));
-
   // Emit the main entry point for the decoder, decodeInstruction().
   emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask);
 

>From 04366eedc71984255b2792be4ff32babd33f3668 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Wed, 2 Jul 2025 06:53:54 -0700
Subject: [PATCH 2/4] Review feedback

---
 llvm/include/llvm/TableGen/Record.h      |   2 +
 llvm/include/llvm/Target/Target.td       |  19 ++++
 llvm/lib/TableGen/Record.cpp             |  43 +++++-----
 llvm/lib/Target/AArch64/AArch64.td       |   6 +-
 llvm/lib/Target/AArch64/CMakeLists.txt   |   3 +-
 llvm/lib/Target/AMDGPU/CMakeLists.txt    |   5 +-
 llvm/lib/Target/ARC/CMakeLists.txt       |   4 +-
 llvm/lib/Target/ARM/CMakeLists.txt       |   4 +-
 llvm/lib/Target/AVR/CMakeLists.txt       |   3 +-
 llvm/lib/Target/BPF/CMakeLists.txt       |   3 +-
 llvm/lib/Target/CSKY/CMakeLists.txt      |   3 +-
 llvm/lib/Target/Hexagon/CMakeLists.txt   |   3 +-
 llvm/lib/Target/Lanai/CMakeLists.txt     |   3 +-
 llvm/lib/Target/LoongArch/CMakeLists.txt |   3 +-
 llvm/lib/Target/MSP430/CMakeLists.txt    |   3 +-
 llvm/lib/Target/Mips/CMakeLists.txt      |   3 +-
 llvm/lib/Target/PowerPC/CMakeLists.txt   |   3 +-
 llvm/lib/Target/RISCV/CMakeLists.txt     |   4 +-
 llvm/lib/Target/RISCV/RISCV.td           |   4 +
 llvm/lib/Target/Sparc/CMakeLists.txt     |   3 +-
 llvm/lib/Target/SystemZ/CMakeLists.txt   |   3 +-
 llvm/lib/Target/VE/CMakeLists.txt        |   3 +-
 llvm/lib/Target/XCore/CMakeLists.txt     |   4 +-
 llvm/lib/Target/Xtensa/CMakeLists.txt    |   3 +-
 llvm/utils/TableGen/DecoderEmitter.cpp   | 105 +++++++++++------------
 25 files changed, 120 insertions(+), 122 deletions(-)

diff --git a/llvm/include/llvm/TableGen/Record.h b/llvm/include/llvm/TableGen/Record.h
index 5849344bcb0b5..306988cd0fc53 100644
--- a/llvm/include/llvm/TableGen/Record.h
+++ b/llvm/include/llvm/TableGen/Record.h
@@ -803,6 +803,8 @@ class ListInit final : public TypedInit,
   size_t size() const { return NumElements; }
   bool empty() const { return NumElements == 0; }
 
+  std::vector<int64_t> getAsListOfInts() const;
+
   const Init *getBit(unsigned Bit) const override {
     llvm_unreachable("Illegal bit reference off list");
   }
diff --git a/llvm/include/llvm/Target/Target.td b/llvm/include/llvm/Target/Target.td
index ce9a2b2751968..e2e711baaede2 100644
--- a/llvm/include/llvm/Target/Target.td
+++ b/llvm/include/llvm/Target/Target.td
@@ -1158,6 +1158,25 @@ class InstrInfo {
   //
   // This option is a temporary migration help. It will go away.
   bit guessInstructionProperties = true;
+
+  // These properties, when set, opt into the non-templated variants of
+  // `decodeToMCInst` generated by TableGen DecoderEmitter backend. Using this
+  // option helps reduce the code size of the generated code as compared to the
+  // templated `decodeToMCInst` that is generated by default.
+  // For each index `I`, InsnCPPTypes[I] is a C++ type that will be used to
+  // generate a non-templated `decodeToMCInst`, and InstBitwidths[I] is a list
+  // instruction bitwidth(s) whose decoders will be included in the generated
+  // code.
+  list<string> InsnCPPTypes = [];
+  list<list<int>> InsnBitwidths = [];
+  assert !eq(!size(InsnCPPTypes), !size(InsnBitwidths)),
+     "The InsnCPPTypes and InsnBitwidths lists must be the same length";
+
+  // Make sure the InstCPPTypes, if not empty, does not contain empty strings.
+  assert !or(!empty(InsnCPPTypes), !empty(!filter(e, InsnCPPTypes, !empty(e)))),
+     "Entries in InstCPPTypes cannot be empty";
+
+  // Make sure that InsnBitwidths, if not empty, does not contain empty list.
 }
 
 // Standard Pseudo Instructions.
diff --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
index 7f2ed77a74099..69f6fa6edb49b 100644
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -804,6 +804,15 @@ std::string ListInit::getAsString() const {
   return Result + "]";
 }
 
+std::vector<int64_t> ListInit::getAsListOfInts() const {
+  if (!isa<IntRecTy>(getElementType()))
+    PrintFatalError("List does not contain integer values");
+  std::vector<int64_t> Ints;
+  for (const Init *I : getElements())
+    Ints.push_back(cast<IntInit>(I)->getValue());
+  return Ints;
+}
+
 const Init *OpInit::getBit(unsigned Bit) const {
   if (getType() == BitRecTy::get(getRecordKeeper()))
     return this;
@@ -3119,32 +3128,26 @@ int64_t Record::getValueAsInt(StringRef FieldName) const {
 std::vector<int64_t>
 Record::getValueAsListOfInts(StringRef FieldName) const {
   const ListInit *List = getValueAsListInit(FieldName);
-  std::vector<int64_t> Ints;
-  for (const Init *I : List->getElements()) {
-    if (const auto *II = dyn_cast<IntInit>(I))
-      Ints.push_back(II->getValue());
-    else
-      PrintFatalError(getLoc(),
-                      Twine("Record `") + getName() + "', field `" + FieldName +
-                          "' exists but does not have a list of ints value: " +
-                          I->getAsString());
-  }
-  return Ints;
+  if (!isa<IntRecTy>(List->getElementType()))
+    PrintFatalError(getLoc(),
+                    Twine("Record `") + getName() + "', field `" + FieldName +
+                        "' exists but does not have a list of ints value: " +
+                        List->getAsString());
+  return List->getAsListOfInts();
 }
 
 std::vector<StringRef>
 Record::getValueAsListOfStrings(StringRef FieldName) const {
   const ListInit *List = getValueAsListInit(FieldName);
+  if (!isa<StringRecTy>(List->getElementType()))
+    PrintFatalError(getLoc(),
+                    Twine("Record `") + getName() + "', field `" + FieldName +
+                        "' exists but does not have a list of string value: " +
+                        List->getAsString());
+
   std::vector<StringRef> Strings;
-  for (const Init *I : List->getElements()) {
-    if (const auto *SI = dyn_cast<StringInit>(I))
-      Strings.push_back(SI->getValue());
-    else
-      PrintFatalError(getLoc(),
-                      Twine("Record `") + getName() + "', field `" + FieldName +
-                          "' exists but does not have a list of strings value: " +
-                          I->getAsString());
-  }
+  for (const Init *I : List->getElements())
+    Strings.push_back(cast<StringInit>(I)->getValue());
   return Strings;
 }
 
diff --git a/llvm/lib/Target/AArch64/AArch64.td b/llvm/lib/Target/AArch64/AArch64.td
index 25cdcae4e41de..670027d59acde 100644
--- a/llvm/lib/Target/AArch64/AArch64.td
+++ b/llvm/lib/Target/AArch64/AArch64.td
@@ -40,7 +40,11 @@ include "AArch64SchedPredExynos.td"
 include "AArch64SchedPredNeoverse.td"
 include "AArch64Combine.td"
 
-def AArch64InstrInfo : InstrInfo;
+def AArch64InstrInfo : InstrInfo {
+  // Opt-in into non-templated code for instruction decoder.
+  let InsnCPPTypes = ["uint32_t"];
+  let InsnBitwidths = [[32]];
+}
 
 //===----------------------------------------------------------------------===//
 // Named operands for MRS/MSR/TLBI/...
diff --git a/llvm/lib/Target/AArch64/CMakeLists.txt b/llvm/lib/Target/AArch64/CMakeLists.txt
index 98cc8693144f0..66136a464f05d 100644
--- a/llvm/lib/Target/AArch64/CMakeLists.txt
+++ b/llvm/lib/Target/AArch64/CMakeLists.txt
@@ -7,8 +7,7 @@ tablegen(LLVM AArch64GenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AArch64GenAsmWriter1.inc -gen-asm-writer -asmwriternum=1)
 tablegen(LLVM AArch64GenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AArch64GenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AArch64GenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM AArch64GenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM AArch64GenFastISel.inc -gen-fast-isel)
 tablegen(LLVM AArch64GenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM AArch64GenO0PreLegalizeGICombiner.inc -gen-global-isel-combiner
diff --git a/llvm/lib/Target/AMDGPU/CMakeLists.txt b/llvm/lib/Target/AMDGPU/CMakeLists.txt
index 6254750c10c3c..e3519f192137c 100644
--- a/llvm/lib/Target/AMDGPU/CMakeLists.txt
+++ b/llvm/lib/Target/AMDGPU/CMakeLists.txt
@@ -6,10 +6,7 @@ tablegen(LLVM AMDGPUGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM AMDGPUGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AMDGPUGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AMDGPUGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AMDGPUGenDisassemblerTables.inc -gen-disassembler
-         -non-templated-decode-to-mcinst-type-spec=uint32_t:=32
-         -non-templated-decode-to-mcinst-type-spec=uint64_t:=64
-         -non-templated-decode-to-mcinst-type-spec=DecoderUInt128:=96,128)
+tablegen(LLVM AMDGPUGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM AMDGPUGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM AMDGPUGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM AMDGPUGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/ARC/CMakeLists.txt b/llvm/lib/Target/ARC/CMakeLists.txt
index e6656576fbcc3..196cc31cc5080 100644
--- a/llvm/lib/Target/ARC/CMakeLists.txt
+++ b/llvm/lib/Target/ARC/CMakeLists.txt
@@ -5,9 +5,7 @@ set(LLVM_TARGET_DEFINITIONS ARC.td)
 tablegen(LLVM ARCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM ARCGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM ARCGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM ARCGenDisassemblerTables.inc -gen-disassembler
-         -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32
-         -non-templated-decode-to-mcinst-type-spec=uint64_t:=48,64)
+tablegen(LLVM ARCGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM ARCGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM ARCGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM ARCGenSDNodeInfo.inc -gen-sd-node-info)
diff --git a/llvm/lib/Target/ARM/CMakeLists.txt b/llvm/lib/Target/ARM/CMakeLists.txt
index 718a084ec6388..a39629bd8aeb0 100644
--- a/llvm/lib/Target/ARM/CMakeLists.txt
+++ b/llvm/lib/Target/ARM/CMakeLists.txt
@@ -6,9 +6,7 @@ tablegen(LLVM ARMGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM ARMGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM ARMGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM ARMGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM ARMGenDisassemblerTables.inc -gen-disassembler
-         -non-templated-decode-to-mcinst-type-spec=uint16_t:=16
-         -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM ARMGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM ARMGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM ARMGenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM ARMGenInstrInfo.inc -gen-instr-info)
diff --git a/llvm/lib/Target/AVR/CMakeLists.txt b/llvm/lib/Target/AVR/CMakeLists.txt
index a2da85d77a325..781dac02c7083 100644
--- a/llvm/lib/Target/AVR/CMakeLists.txt
+++ b/llvm/lib/Target/AVR/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM AVRGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM AVRGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM AVRGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM AVRGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM AVRGenDisassemblerTables.inc -gen-disassembler
-         -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
+tablegen(LLVM AVRGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM AVRGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM AVRGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM AVRGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/BPF/CMakeLists.txt b/llvm/lib/Target/BPF/CMakeLists.txt
index 6a609d645dfa1..eade4cacb7100 100644
--- a/llvm/lib/Target/BPF/CMakeLists.txt
+++ b/llvm/lib/Target/BPF/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM BPFGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM BPFGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM BPFGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM BPFGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM BPFGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint64_t:=64)
+tablegen(LLVM BPFGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM BPFGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM BPFGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM BPFGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/CSKY/CMakeLists.txt b/llvm/lib/Target/CSKY/CMakeLists.txt
index eadf0169edef1..4b900bc99c271 100644
--- a/llvm/lib/Target/CSKY/CMakeLists.txt
+++ b/llvm/lib/Target/CSKY/CMakeLists.txt
@@ -7,8 +7,7 @@ tablegen(LLVM CSKYGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM CSKYGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM CSKYGenCompressInstEmitter.inc -gen-compress-inst-emitter)
 tablegen(LLVM CSKYGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM CSKYGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
+tablegen(LLVM CSKYGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM CSKYGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM CSKYGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM CSKYGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/Hexagon/CMakeLists.txt b/llvm/lib/Target/Hexagon/CMakeLists.txt
index be2bc89155612..d758260a8ab5d 100644
--- a/llvm/lib/Target/Hexagon/CMakeLists.txt
+++ b/llvm/lib/Target/Hexagon/CMakeLists.txt
@@ -7,8 +7,7 @@ tablegen(LLVM HexagonGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM HexagonGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM HexagonGenDAGISel.inc -gen-dag-isel)
 tablegen(LLVM HexagonGenDFAPacketizer.inc -gen-dfa-packetizer)
-tablegen(LLVM HexagonGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM HexagonGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM HexagonGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM HexagonGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM HexagonGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/Lanai/CMakeLists.txt b/llvm/lib/Target/Lanai/CMakeLists.txt
index dfb0c93e1a5e3..4a628e13fc177 100644
--- a/llvm/lib/Target/Lanai/CMakeLists.txt
+++ b/llvm/lib/Target/Lanai/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM LanaiGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM LanaiGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM LanaiGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM LanaiGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM LanaiGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM LanaiGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM LanaiGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM LanaiGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM LanaiGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/LoongArch/CMakeLists.txt b/llvm/lib/Target/LoongArch/CMakeLists.txt
index c851f5c2fc1da..0f674b1b0fa9e 100644
--- a/llvm/lib/Target/LoongArch/CMakeLists.txt
+++ b/llvm/lib/Target/LoongArch/CMakeLists.txt
@@ -5,8 +5,7 @@ set(LLVM_TARGET_DEFINITIONS LoongArch.td)
 tablegen(LLVM LoongArchGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM LoongArchGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM LoongArchGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM LoongArchGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM LoongArchGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM LoongArchGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM LoongArchGenMCPseudoLowering.inc -gen-pseudo-lowering)
 tablegen(LLVM LoongArchGenMCCodeEmitter.inc -gen-emitter)
diff --git a/llvm/lib/Target/MSP430/CMakeLists.txt b/llvm/lib/Target/MSP430/CMakeLists.txt
index f10c8192e7df0..4081d3472fd78 100644
--- a/llvm/lib/Target/MSP430/CMakeLists.txt
+++ b/llvm/lib/Target/MSP430/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM MSP430GenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM MSP430GenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM MSP430GenCallingConv.inc -gen-callingconv)
 tablegen(LLVM MSP430GenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM MSP430GenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,32,48)
+tablegen(LLVM MSP430GenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM MSP430GenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM MSP430GenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM MSP430GenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/Mips/CMakeLists.txt b/llvm/lib/Target/Mips/CMakeLists.txt
index 2516d00706a91..21d1765107ae6 100644
--- a/llvm/lib/Target/Mips/CMakeLists.txt
+++ b/llvm/lib/Target/Mips/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM MipsGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM MipsGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM MipsGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM MipsGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM MipsGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32)
+tablegen(LLVM MipsGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM MipsGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM MipsGenGlobalISel.inc -gen-global-isel)
 tablegen(LLVM MipsGenPostLegalizeGICombiner.inc -gen-global-isel-combiner
diff --git a/llvm/lib/Target/PowerPC/CMakeLists.txt b/llvm/lib/Target/PowerPC/CMakeLists.txt
index 136db0634eb93..3808a26a0b92a 100644
--- a/llvm/lib/Target/PowerPC/CMakeLists.txt
+++ b/llvm/lib/Target/PowerPC/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM PPCGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM PPCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM PPCGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM PPCGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler
-               -non-templated-decode-to-mcinst-type-spec=uint64_t:=32,64)
+tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM PPCGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM PPCGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM PPCGenMCCodeEmitter.inc -gen-emitter)
diff --git a/llvm/lib/Target/RISCV/CMakeLists.txt b/llvm/lib/Target/RISCV/CMakeLists.txt
index 9df6701387d43..e32d6eab3b977 100644
--- a/llvm/lib/Target/RISCV/CMakeLists.txt
+++ b/llvm/lib/Target/RISCV/CMakeLists.txt
@@ -7,9 +7,7 @@ tablegen(LLVM RISCVGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM RISCVGenCompressInstEmitter.inc -gen-compress-inst-emitter)
 tablegen(LLVM RISCVGenMacroFusion.inc -gen-macro-fusion-pred)
 tablegen(LLVM RISCVGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM RISCVGenDisassemblerTables.inc -gen-disassembler
-              -non-templated-decode-to-mcinst-type-spec=uint32_t:=16,32
-              -non-templated-decode-to-mcinst-type-spec=uint64_t:=48)
+tablegen(LLVM RISCVGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM RISCVGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM RISCVGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM RISCVGenMCPseudoLowering.inc -gen-pseudo-lowering)
diff --git a/llvm/lib/Target/RISCV/RISCV.td b/llvm/lib/Target/RISCV/RISCV.td
index b24d8637cb27f..b3ce392d27a17 100644
--- a/llvm/lib/Target/RISCV/RISCV.td
+++ b/llvm/lib/Target/RISCV/RISCV.td
@@ -85,6 +85,10 @@ include "RISCVPfmCounters.td"
 
 def RISCVInstrInfo : InstrInfo {
   let guessInstructionProperties = 0;
+
+  // Opt-in into non-templated code for instruction decoder.
+  let InsnCPPTypes = ["uint64_t"];
+  let InsnBitwidths = [[16, 32, 48]];
 }
 
 def RISCVAsmParser : AsmParser {
diff --git a/llvm/lib/Target/Sparc/CMakeLists.txt b/llvm/lib/Target/Sparc/CMakeLists.txt
index 6334dbbc6cc1a..f682719ac483f 100644
--- a/llvm/lib/Target/Sparc/CMakeLists.txt
+++ b/llvm/lib/Target/Sparc/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM SparcGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM SparcGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM SparcGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM SparcGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM SparcGenDisassemblerTables.inc -gen-disassembler
-               -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM SparcGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM SparcGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM SparcGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM SparcGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/SystemZ/CMakeLists.txt b/llvm/lib/Target/SystemZ/CMakeLists.txt
index 1caeef468f3fb..0d8f3eac6ee4f 100644
--- a/llvm/lib/Target/SystemZ/CMakeLists.txt
+++ b/llvm/lib/Target/SystemZ/CMakeLists.txt
@@ -7,8 +7,7 @@ tablegen(LLVM SystemZGenGNUAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM SystemZGenHLASMAsmWriter.inc -gen-asm-writer -asmwriternum=1)
 tablegen(LLVM SystemZGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM SystemZGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM SystemZGenDisassemblerTables.inc -gen-disassembler
-               -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,32,48)
+tablegen(LLVM SystemZGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM SystemZGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM SystemZGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM SystemZGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/lib/Target/VE/CMakeLists.txt b/llvm/lib/Target/VE/CMakeLists.txt
index 6b83a3e7ae28e..d1bb4f32fcba7 100644
--- a/llvm/lib/Target/VE/CMakeLists.txt
+++ b/llvm/lib/Target/VE/CMakeLists.txt
@@ -4,8 +4,7 @@ set(LLVM_TARGET_DEFINITIONS VE.td)
 
 tablegen(LLVM VEGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM VEGenInstrInfo.inc -gen-instr-info)
-tablegen(LLVM VEGenDisassemblerTables.inc -gen-disassembler
-               -non-templated-decode-to-mcinst-type-spec=uint64_t:=64)
+tablegen(LLVM VEGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM VEGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM VEGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM VEGenAsmMatcher.inc -gen-asm-matcher)
diff --git a/llvm/lib/Target/XCore/CMakeLists.txt b/llvm/lib/Target/XCore/CMakeLists.txt
index 3b5bf848d8144..f411c658b43b0 100644
--- a/llvm/lib/Target/XCore/CMakeLists.txt
+++ b/llvm/lib/Target/XCore/CMakeLists.txt
@@ -5,9 +5,7 @@ set(LLVM_TARGET_DEFINITIONS XCore.td)
 tablegen(LLVM XCoreGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM XCoreGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM XCoreGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM XCoreGenDisassemblerTables.inc -gen-disassembler
-          -non-templated-decode-to-mcinst-type-spec=uint16_t:=16
-          -non-templated-decode-to-mcinst-type-spec=uint32_t:=32)
+tablegen(LLVM XCoreGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM XCoreGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM XCoreGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM XCoreGenSDNodeInfo.inc -gen-sd-node-info)
diff --git a/llvm/lib/Target/Xtensa/CMakeLists.txt b/llvm/lib/Target/Xtensa/CMakeLists.txt
index 9c825b5d880c7..4fc1ba6dfa650 100644
--- a/llvm/lib/Target/Xtensa/CMakeLists.txt
+++ b/llvm/lib/Target/Xtensa/CMakeLists.txt
@@ -6,8 +6,7 @@ tablegen(LLVM XtensaGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM XtensaGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM XtensaGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM XtensaGenDAGISel.inc -gen-dag-isel)
-tablegen(LLVM XtensaGenDisassemblerTables.inc -gen-disassembler
-               -non-templated-decode-to-mcinst-type-spec=uint64_t:=16,24)
+tablegen(LLVM XtensaGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM XtensaGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM XtensaGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM XtensaGenRegisterInfo.inc -gen-register-info)
diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index ae3f072601014..7656baddccba1 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -93,22 +93,6 @@ static cl::opt<bool> UseFnTableInDecodeToMCInst(
         "of the generated code."),
     cl::init(false), cl::cat(DisassemblerEmitterCat));
 
-// Option to generate a non-templated version of `decodeToMCInst`. The
-// templated `decodeToMCInst` is templated on `InsnType` and a given `InsnType`
-// can target instructions with one or more Bitwidths. So the option to
-// generate a non-templated `decodeToMCInst` is a typespec of the form
-// type::=list-of-sizes.
-
-// For example, for the AMDGPU target, the type `DecoderUInt128` is used for
-// both 96 and 128 bit instructions. So the generated non-templated
-// `decodeToMCInst` will support decoding both these instruction Bitwidths and
-// the option will be DecoderUInt128::=96,128
-static cl::list<std::string> DecodeToMCInstTypeSpecs(
-    "non-templated-decode-to-mcinst-type-spec",
-    cl::desc("list of C++ types and associated bitwidths to used to generate "
-             "non-templated `decodeToMCInst`."),
-    cl::cat(DisassemblerEmitterCat));
-
 STATISTIC(NumEncodings, "Number of encodings considered");
 STATISTIC(NumEncodingsLackingDisasm,
           "Number of encodings without disassembler info");
@@ -233,6 +217,14 @@ struct EncodingIDAndOpcode {
 using EncodingIDsVec = std::vector<EncodingIDAndOpcode>;
 using NamespacesHwModesMap = std::map<std::string, std::set<StringRef>>;
 
+// Result of parsing the `InsnCPPTypes` and `InstBitwidths` fields in the Target
+// instruction set.
+using BitwidthSet = SmallSet<unsigned, 4>;
+struct NonTemplatedInsnType {
+  StringRef CPPType;
+  BitwidthSet Bitwidths;
+};
+
 class DecoderEmitter {
   const RecordKeeper &RK;
   std::vector<EncodingAndInst> NumberedEncodings;
@@ -257,6 +249,8 @@ class DecoderEmitter {
   void run(raw_ostream &o);
 
 private:
+  SmallVector<NonTemplatedInsnType>
+  parseNonTemplatedInsnTypes(BitwidthSet &InstrBitwidths);
   CodeGenTarget Target;
 
 public:
@@ -2565,66 +2559,63 @@ handleHwModesUnrelatedEncodings(const CodeGenInstruction *Instr,
     break;
   }
 }
+SmallVector<NonTemplatedInsnType>
+DecoderEmitter::parseNonTemplatedInsnTypes(BitwidthSet &InstrBitwidths) {
+  SmallVector<NonTemplatedInsnType> Parsed;
 
-// Result of parsing a single `non-templated-decode-to-mcinst-type-spec` option.
-using BitwidthSet = SmallSet<unsigned, 4>;
-struct NonTemplatedTypeSpec {
-  StringRef Type;
-  BitwidthSet Bitwidths;
-};
+  const Record *InstructionSet = Target.getInstructionSet();
+  std::vector<StringRef> InsnCPPTypes =
+      InstructionSet->getValueAsListOfStrings("InsnCPPTypes");
 
-static SmallVector<NonTemplatedTypeSpec>
-parseNonTemplatedTypeSpec(BitwidthSet &InstrBitwidths) {
-  SmallVector<NonTemplatedTypeSpec> Parsed;
-  if (DecodeToMCInstTypeSpecs.empty()) {
-    // If no `non-templated-decode-to-mcinst-type-spec` option is specified,
+  if (InsnCPPTypes.empty()) {
+    // If no `InsnCPPTypes` is specified in the instruction info,
     // create a type-spec with empty values, which will trigger generation of
     // a templated `decodeToMCInst`.
     Parsed.emplace_back();
     return Parsed;
   }
 
-  Parsed.reserve(DecodeToMCInstTypeSpecs.size());
+  // Use field locations for error reporting.
+  SMLoc CPPTypesLoc = InstructionSet->getFieldLoc("InsnCPPTypes");
+  SMLoc BitwidthsLoc = InstructionSet->getFieldLoc("InsnBitwidths");
+
+  const ListInit *InsnBitwidths =
+      InstructionSet->getValueAsListInit("InsnBitwidths");
+
+  Parsed.reserve(InsnCPPTypes.size());
   BitwidthSet OptionBitwidths;
 
-  for (StringRef TypeSpec : DecodeToMCInstTypeSpecs) {
+  for (const auto &[CPPType, BWL] :
+       zip_equal(InsnCPPTypes, InsnBitwidths->getElements())) {
     BitwidthSet Bitwidths;
-    // Each `non-templated-decode-to-mcinst-type-spec` is of the form
-    // <type>:=<list of bitwidths>. Note, <type> can in general be a templated
-    // type, so using the token ":=" as a separator to allow many general C++
-    // types here.
-    auto [Type, ListOfBitWidths] = TypeSpec.split(":=");
-    if (Type.empty())
-      PrintFatalError("Invalid typespec: " + TypeSpec);
-
-    for (StringRef BwStr : split(ListOfBitWidths, ',')) {
-      unsigned Bitwidth;
-      if (BwStr.getAsInteger(10, Bitwidth))
-        PrintFatalError("Invalid bitwidth: " + BwStr + " in typespec " +
-                        TypeSpec);
-
+    if (CPPType.empty())
+      PrintFatalError(CPPTypesLoc,
+                      "CPP Type cannot be empty in `InsnCPPTypes`");
+    const auto *BitwidthList = dyn_cast<ListInit>(BWL);
+    if (!BitwidthList || BitwidthList->empty())
+      PrintFatalError(BitwidthsLoc,
+                      "No bitwidths specified for InsnCPPType : " + CPPType);
+
+    for (int64_t Bitwidth : BitwidthList->getAsListOfInts()) {
       if (!OptionBitwidths.insert(Bitwidth).second)
-        PrintFatalError("Bitwidth " + Twine(Bitwidth) + " already specified.");
+        PrintFatalError(BitwidthsLoc,
+                        "Bitwidth " + Twine(Bitwidth) + " already specified.");
 
       if (!InstrBitwidths.contains(Bitwidth))
-        PrintFatalError(Twine("No instruction of Bitwidth ") + Twine(Bitwidth) +
-                        " supported.");
-
+        PrintFatalError(BitwidthsLoc, "No instruction of bitwidth " +
+                                          Twine(Bitwidth) + " supported.");
       InstrBitwidths.erase(Bitwidth);
       Bitwidths.insert(Bitwidth);
     }
-
-    if (Bitwidths.empty())
-      PrintFatalError("No bitwidth specified in typespec " + TypeSpec);
-
-    Parsed.emplace_back(NonTemplatedTypeSpec{Type, Bitwidths});
+    Parsed.emplace_back(NonTemplatedInsnType{CPPType, Bitwidths});
   }
 
   if (!InstrBitwidths.empty()) {
+    // FIXME: Add PrintFatalError that accepts a location and a function_ref.
     PrintFatalError([&InstrBitwidths](raw_ostream &OS) {
       OS << "Bitwidth(s) ";
-      llvm::interleaveComma(InstrBitwidths, OS);
-      OS << " missing in `non-templated-decode-to-mcinst-type-spec` options.";
+      interleaveComma(InstrBitwidths, OS);
+      OS << " missing in `InsnBitwidths`";
     });
   }
   return Parsed;
@@ -2747,12 +2738,12 @@ namespace {
     const unsigned Bitwidth = 8 * NSAndByteSize.second;
     InstrBitwidths.insert(Bitwidth);
   }
-  SmallVector<NonTemplatedTypeSpec> NonTemplatedTypeSpecs =
-      parseNonTemplatedTypeSpec(InstrBitwidths);
+  SmallVector<NonTemplatedInsnType> NonTemplatedInsnTypes =
+      parseNonTemplatedInsnTypes(InstrBitwidths);
 
   DecoderTableInfo TableInfo;
   unsigned OpcodeMask = 0;
-  for (const auto &[NTType, NTBitwidths] : NonTemplatedTypeSpecs) {
+  for (const auto &[NTType, NTBitwidths] : NonTemplatedInsnTypes) {
     // Reset the Decoders for each non-templated type.
     TableInfo.Decoders.clear();
 

>From 26588554e04dc9641c323d11fe0f0a40f230f5d7 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Wed, 2 Jul 2025 14:31:28 -0700
Subject: [PATCH 3/4] Specialize decodeInstruction

---
 llvm/utils/TableGen/DecoderEmitter.cpp | 27 ++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index 7656baddccba1..00123c62b6724 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -2261,7 +2261,8 @@ static void insertBits(InsnType &field, InsnType bits, unsigned startBit,
 // emitDecodeInstruction - Emit the templated helper function
 // decodeInstruction().
 static void emitDecodeInstruction(formatted_raw_ostream &OS, bool IsVarLenInst,
-                                  unsigned OpcodeMask) {
+                                  unsigned OpcodeMask,
+                                  StringRef SpecializedInsnType) {
   const bool HasTryDecode = OpcodeMask & ((1 << MCD::OPC_TryDecode) |
                                           (1 << MCD::OPC_TryDecodeOrFail));
   const bool HasCheckPredicate =
@@ -2269,6 +2270,14 @@ static void emitDecodeInstruction(formatted_raw_ostream &OS, bool IsVarLenInst,
       ((1 << MCD::OPC_CheckPredicate) | (1 << MCD::OPC_CheckPredicateOrFail));
   const bool HasSoftFail = OpcodeMask & (1 << MCD::OPC_SoftFail);
 
+  auto emitTemplate = [&OS, SpecializedInsnType] {
+    if (SpecializedInsnType.empty())
+      OS << "template <typename InsnType>\n";
+  };
+
+  StringRef InsnType =
+      SpecializedInsnType.empty() ? "InsnType" : SpecializedInsnType;
+
   OS << R"(
 static unsigned decodeNumToSkip(const uint8_t *&Ptr) {
   unsigned NumToSkip = *Ptr++;
@@ -2277,11 +2286,13 @@ static unsigned decodeNumToSkip(const uint8_t *&Ptr) {
   if (getNumToSkipInBytes() == 3)
     OS << "  NumToSkip |= (*Ptr++) << 16;\n";
   OS << R"(  return NumToSkip;
-}
+})";
 
-template <typename InsnType>
-static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
-                                      InsnType insn, uint64_t Address,
+  emitTemplate();
+  OS << R"(
+static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI, )";
+  OS << InsnType << " insn,\n";
+  OS << R"(                             uint64_t Address,
                                       const MCDisassembler *DisAsm,
                                       const MCSubtargetInfo &STI)";
   if (IsVarLenInst) {
@@ -2802,7 +2813,11 @@ namespace {
     emitPredicateFunction(OS, TableInfo.Predicates, indent(0));
 
   // Emit the main entry point for the decoder, decodeInstruction().
-  emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask);
+  // Generate non-templated code if exactly one InsnCPPType was specified.
+  StringRef SpecializedInsnType =
+      NonTemplatedInsnTypes.size() == 1 ? NonTemplatedInsnTypes[0].CPPType : "";
+
+  emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask, SpecializedInsnType);
 
   OS << "\n} // namespace\n";
 }

>From 1ecd40edc67b7222fa2a45b12a005cef94888086 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Thu, 3 Jul 2025 17:00:22 -0700
Subject: [PATCH 4/4] Full specialization

---
 llvm/include/llvm/Target/Target.td            |  37 +--
 llvm/lib/Target/AArch64/AArch64.td            |   6 +-
 llvm/lib/Target/AMDGPU/AMDGPU.td              |   7 +
 .../Disassembler/AMDGPUDisassembler.cpp       |   2 +-
 .../M68k/Disassembler/M68kDisassembler.cpp    |   4 +-
 llvm/lib/Target/RISCV/RISCV.td                |   4 -
 llvm/test/TableGen/DecoderEmitterFnTable.td   |  10 +-
 llvm/test/TableGen/VarLenDecoder.td           |  12 +-
 llvm/test/TableGen/trydecode-emission.td      |  20 +-
 llvm/utils/TableGen/DecoderEmitter.cpp        | 295 ++++++++++++------
 10 files changed, 243 insertions(+), 154 deletions(-)

diff --git a/llvm/include/llvm/Target/Target.td b/llvm/include/llvm/Target/Target.td
index e2e711baaede2..643441bec4268 100644
--- a/llvm/include/llvm/Target/Target.td
+++ b/llvm/include/llvm/Target/Target.td
@@ -1137,6 +1137,15 @@ class OptionalDefOperand<ValueType ty, dag OpTypes, dag defaultops>
   let MIOperandInfo = OpTypes;
 }
 
+// InstrDecoderOption - This class is used to provide some options to the
+// TableGen DecoderEmitter backend.
+class InstrDecoderOption<string ty, list<int> bws> {
+  string CPPType = ty;       // C++ type for generating non-templated code.
+  list<int> Bitwidths = bws; // List of bitwidths supported by the above type.
+
+  assert !not(!empty(CPPType)), "CPP type cannot be empty";
+  assert !not(!empty(Bitwidths)), "Bitwidths cannot be empty";
+}
 
 // InstrInfo - This class should only be instantiated once to provide parameters
 // which are global to the target machine.
@@ -1159,24 +1168,16 @@ class InstrInfo {
   // This option is a temporary migration help. It will go away.
   bit guessInstructionProperties = true;
 
-  // These properties, when set, opt into the non-templated variants of
-  // `decodeToMCInst` generated by TableGen DecoderEmitter backend. Using this
-  // option helps reduce the code size of the generated code as compared to the
-  // templated `decodeToMCInst` that is generated by default.
-  // For each index `I`, InsnCPPTypes[I] is a C++ type that will be used to
-  // generate a non-templated `decodeToMCInst`, and InstBitwidths[I] is a list
-  // instruction bitwidth(s) whose decoders will be included in the generated
-  // code.
-  list<string> InsnCPPTypes = [];
-  list<list<int>> InsnBitwidths = [];
-  assert !eq(!size(InsnCPPTypes), !size(InsnBitwidths)),
-     "The InsnCPPTypes and InsnBitwidths lists must be the same length";
-
-  // Make sure the InstCPPTypes, if not empty, does not contain empty strings.
-  assert !or(!empty(InsnCPPTypes), !empty(!filter(e, InsnCPPTypes, !empty(e)))),
-     "Entries in InstCPPTypes cannot be empty";
-
-  // Make sure that InsnBitwidths, if not empty, does not contain empty list.
+  // This is a list of instruction decoder options for this target. When non
+  // empty, it should list all the C++ types and associated bitwidths that this
+  // target intends to use to call the TableGen generated `decodeInstruction`
+  // function. If this list is empty, the decoder emitter will generate
+  // templated code. However, if a target intends to call this function with
+  // more than one `InsnType`, it may be beneficial to provide these decoder
+  // options to generate non-templated form of `decodeInstruction` and
+  // associated helper functions and avoid some code duplication in the
+  // `decodeToMCInst` function.
+  list<InstrDecoderOption> DecoderOptions = [];
 }
 
 // Standard Pseudo Instructions.
diff --git a/llvm/lib/Target/AArch64/AArch64.td b/llvm/lib/Target/AArch64/AArch64.td
index 670027d59acde..25cdcae4e41de 100644
--- a/llvm/lib/Target/AArch64/AArch64.td
+++ b/llvm/lib/Target/AArch64/AArch64.td
@@ -40,11 +40,7 @@ include "AArch64SchedPredExynos.td"
 include "AArch64SchedPredNeoverse.td"
 include "AArch64Combine.td"
 
-def AArch64InstrInfo : InstrInfo {
-  // Opt-in into non-templated code for instruction decoder.
-  let InsnCPPTypes = ["uint32_t"];
-  let InsnBitwidths = [[32]];
-}
+def AArch64InstrInfo : InstrInfo;
 
 //===----------------------------------------------------------------------===//
 // Named operands for MRS/MSR/TLBI/...
diff --git a/llvm/lib/Target/AMDGPU/AMDGPU.td b/llvm/lib/Target/AMDGPU/AMDGPU.td
index 1a1c32fba9d18..0ce66f7b88cb1 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPU.td
+++ b/llvm/lib/Target/AMDGPU/AMDGPU.td
@@ -1973,6 +1973,13 @@ def FeatureISAVersion12_Generic: FeatureSet<
 
 def AMDGPUInstrInfo : InstrInfo {
   let guessInstructionProperties = 1;
+
+  // Opt-in into non-templated code for instruction decoder.
+  let DecoderOptions = [
+    InstrDecoderOption<"uint32_t", [32]>,
+    InstrDecoderOption<"uint64_t", [64]>,
+    InstrDecoderOption<"DecoderUInt128", [96, 128]>,
+  ];
 }
 
 def AMDGPUAsmParser : AsmParser {
diff --git a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
index 59c72fcbff18a..cd582de176c25 100644
--- a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
+++ b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
@@ -591,7 +591,7 @@ DecodeStatus AMDGPUDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
 
     // Try to decode DPP and SDWA first to solve conflict with VOP1 and VOP2
     // encodings
-    if (isGFX11Plus() && Bytes.size() >= 12 ) {
+    if (isGFX11Plus() && Bytes.size() >= 12) {
       DecoderUInt128 DecW = eat12Bytes(Bytes);
 
       if (isGFX11() &&
diff --git a/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp b/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
index 4ec18fe6bf544..ee453cfc0924e 100644
--- a/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
+++ b/llvm/lib/Target/M68k/Disassembler/M68kDisassembler.cpp
@@ -111,13 +111,13 @@ static DecodeStatus DecodeFPCSCRegisterClass(MCInst &Inst, uint64_t RegNo,
 }
 #define DecodeFPICRegisterClass DecodeFPCSCRegisterClass
 
-static DecodeStatus DecodeCCRCRegisterClass(MCInst &Inst, APInt &Insn,
+static DecodeStatus DecodeCCRCRegisterClass(MCInst &Inst, const APInt &Insn,
                                             uint64_t Address,
                                             const void *Decoder) {
   llvm_unreachable("unimplemented");
 }
 
-static DecodeStatus DecodeSRCRegisterClass(MCInst &Inst, APInt &Insn,
+static DecodeStatus DecodeSRCRegisterClass(MCInst &Inst, const APInt &Insn,
                                            uint64_t Address,
                                            const void *Decoder) {
   llvm_unreachable("unimplemented");
diff --git a/llvm/lib/Target/RISCV/RISCV.td b/llvm/lib/Target/RISCV/RISCV.td
index b3ce392d27a17..b24d8637cb27f 100644
--- a/llvm/lib/Target/RISCV/RISCV.td
+++ b/llvm/lib/Target/RISCV/RISCV.td
@@ -85,10 +85,6 @@ include "RISCVPfmCounters.td"
 
 def RISCVInstrInfo : InstrInfo {
   let guessInstructionProperties = 0;
-
-  // Opt-in into non-templated code for instruction decoder.
-  let InsnCPPTypes = ["uint64_t"];
-  let InsnBitwidths = [[16, 32, 48]];
 }
 
 def RISCVAsmParser : AsmParser {
diff --git a/llvm/test/TableGen/DecoderEmitterFnTable.td b/llvm/test/TableGen/DecoderEmitterFnTable.td
index 7bed18c19a513..837ec3bdc5c84 100644
--- a/llvm/test/TableGen/DecoderEmitterFnTable.td
+++ b/llvm/test/TableGen/DecoderEmitterFnTable.td
@@ -71,11 +71,11 @@ def Inst3 : TestInstruction {
   let AsmString = "Inst3";
 }
 
-// CHECK-LABEL: DecodeStatus decodeFn0(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
-// CHECK-LABEL: DecodeStatus decodeFn1(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
-// CHECK-LABEL: DecodeStatus decodeFn2(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
-// CHECK-LABEL: DecodeStatus decodeFn3(DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
-// CHECK-LABEL: decodeToMCInst(unsigned Idx, DecodeStatus S, InsnType insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
+// CHECK-LABEL: DecodeStatus decodeFn0(DecodeStatus S, const InsnType &insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
+// CHECK-LABEL: DecodeStatus decodeFn1(DecodeStatus S, const InsnType &insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
+// CHECK-LABEL: DecodeStatus decodeFn2(DecodeStatus S, const InsnType &insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
+// CHECK-LABEL: DecodeStatus decodeFn3(DecodeStatus S, const InsnType &insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
+// CHECK-LABEL: decodeToMCInst(unsigned Idx, DecodeStatus S, const InsnType &insn, MCInst &MI, uint64_t Address, const MCDisassembler *Decoder, bool &DecodeComplete)
 // CHECK: static constexpr DecodeFnTy decodeFnTable[]
 // CHECK-NEXT: decodeFn0,
 // CHECK-NEXT: decodeFn1,
diff --git a/llvm/test/TableGen/VarLenDecoder.td b/llvm/test/TableGen/VarLenDecoder.td
index 2359bd2c15145..d438e64264cbd 100644
--- a/llvm/test/TableGen/VarLenDecoder.td
+++ b/llvm/test/TableGen/VarLenDecoder.td
@@ -47,6 +47,12 @@ def FOO32 : MyVarInst<MemOp32> {
   );
 }
 
+// Instruction length table
+// CHECK-LABEL: InstrLenTable
+// CHECK: 27,
+// CHECK-NEXT: 43,
+// CHECK-NEXT: };
+
 // CHECK-SMALL:      /* 0 */       MCD::OPC_ExtractField, 3, 5,  // Inst{7-3} ...
 // CHECK-SMALL-NEXT: /* 3 */       MCD::OPC_FilterValue, 8, 4, 0, // Skip to: 11
 // CHECK-SMALL-NEXT: /* 7 */       MCD::OPC_Decode, {{[0-9]+}}, {{[0-9]+}}, 0, // Opcode: FOO16
@@ -81,12 +87,6 @@ def FOO32 : MyVarInst<MemOp32> {
 // CHECK-NEXT: MI.addOperand(MCOperand::createImm(tmp));
 // CHECK-NEXT: return S;
 
-// Instruction length table
-// CHECK-LABEL: InstrLenTable
-// CHECK: 27,
-// CHECK-NEXT: 43,
-// CHECK-NEXT: };
-
 // CHECK-LABEL: decodeInstruction
 // CHECK-LABEL: case MCD::OPC_ExtractField: {
 // CHECK: makeUp(insn, Start + Len);
diff --git a/llvm/test/TableGen/trydecode-emission.td b/llvm/test/TableGen/trydecode-emission.td
index c3178dd71cf4b..8e427c8a7107b 100644
--- a/llvm/test/TableGen/trydecode-emission.td
+++ b/llvm/test/TableGen/trydecode-emission.td
@@ -34,6 +34,17 @@ def InstB : TestInstruction {
   let hasCompleteDecoder = 0;
 }
 
+// CHECK-LABEL: decodeNumToSkip
+// CHECK-NEXT:  unsigned NumToSkip = *Ptr++;
+// CHECK-NEXT:  NumToSkip |= (*Ptr++) << 8;
+// CHECK-NEXT:  return NumToSkip;
+
+// CHECK-LARGE-LABEL: decodeNumToSkip
+// CHECK-LARGE-NEXT:  unsigned NumToSkip = *Ptr++;
+// CHECK-LARGE-NEXT:  NumToSkip |= (*Ptr++) << 8;
+// CHECK-LARGE-NEXT:  NumToSkip |= (*Ptr++) << 16;
+// CHECK-LARGE-NEXT:  return NumToSkip;
+
 // CHECK:      /* 0 */       MCD::OPC_ExtractField, 4, 4,  // Inst{7-4} ...
 // CHECK-NEXT: /* 3 */       MCD::OPC_FilterValueOrFail, 0,
 // CHECK-NEXT: /* 5 */       MCD::OPC_CheckField, 2, 2, 0, 6, 0, // Skip to: 17
@@ -43,10 +54,6 @@ def InstB : TestInstruction {
 
 // CHECK: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
 
-// CHECK:       unsigned NumToSkip = *Ptr++;
-// CHECK-NEXT:  NumToSkip |= (*Ptr++) << 8;
-// CHECK-NEXT:  return NumToSkip;
-
 // CHECK-LARGE:      /* 0 */       MCD::OPC_ExtractField, 4, 4,  // Inst{7-4} ...
 // CHECK-LARGE-NEXT: /* 3 */       MCD::OPC_FilterValueOrFail, 0,
 // CHECK-LARGE-NEXT: /* 5 */       MCD::OPC_CheckField, 2, 2, 0, 7, 0, 0, // Skip to: 19
@@ -55,8 +62,3 @@ def InstB : TestInstruction {
 // CHECK-LARGE-NEXT: /* 23 */      MCD::OPC_Fail,
 
 // CHECK-LARGE: if (!Check(S, DecodeInstB(MI, insn, Address, Decoder))) { DecodeComplete = false; return MCDisassembler::Fail; }
-
-// CHECK-LARGE:       unsigned NumToSkip = *Ptr++;
-// CHECK-LARGE-NEXT:  NumToSkip |= (*Ptr++) << 8;
-// CHECK-LARGE-NEXT:  NumToSkip |= (*Ptr++) << 16;
-// CHECK-LARGE-NEXT:  return NumToSkip;
diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index 00123c62b6724..d7c37f112cd44 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -223,6 +223,9 @@ using BitwidthSet = SmallSet<unsigned, 4>;
 struct NonTemplatedInsnType {
   StringRef CPPType;
   BitwidthSet Bitwidths;
+
+  NonTemplatedInsnType(StringRef CPPType, BitwidthSet Bitwidths)
+      : CPPType(CPPType), Bitwidths(std::move(Bitwidths)) {}
 };
 
 class DecoderEmitter {
@@ -1077,21 +1080,25 @@ void DecoderEmitter::emitPredicateFunction(formatted_raw_ostream &OS,
   OS << Indent << "}\n\n";
 }
 
+static void emitTemplate(formatted_raw_ostream &OS,
+                         StringRef SpecializedInsnType) {
+  if (SpecializedInsnType.empty())
+    OS << "template <typename InsnType>\n";
+}
+
+static StringRef getInsnType(StringRef SpecializedInsnType) {
+  return SpecializedInsnType.empty() ? "InsnType" : SpecializedInsnType;
+}
+
 void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
                                          DecoderSet &Decoders,
                                          StringRef SpecializedInsnType,
                                          indent Indent) const {
-  auto emitTemplate = [&OS, SpecializedInsnType, &Indent] {
-    if (SpecializedInsnType.empty())
-      OS << Indent << "template <typename InsnType>\n";
-  };
-
-  StringRef InsnType =
-      SpecializedInsnType.empty() ? "InsnType" : SpecializedInsnType;
-
   // The decoder function is just a big switch statement or a table of function
   // pointers based on the input decoder index.
 
+  StringRef InsnType = getInsnType(SpecializedInsnType);
+
   // TODO: When InsnType is large, using uint64_t limits all fields to 64 bits
   // It would be better for emitBinaryParser to use a 64-bit tmp whenever
   // possible but fall back to an InsnType-sized tmp for truly large fields.
@@ -1100,14 +1107,14 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
       "uint64_t>;\n",
       InsnType);
   auto DecodeParams =
-      formatv("DecodeStatus S, {} insn, MCInst &MI, uint64_t Address, const "
-              "MCDisassembler *Decoder, bool &DecodeComplete",
+      formatv("DecodeStatus S, const {} &insn, MCInst &MI, uint64_t Address, "
+              "const MCDisassembler *Decoder, bool &DecodeComplete",
               InsnType);
 
   if (UseFnTableInDecodeToMCInst) {
     // Emit a function for each case first.
     for (const auto &[Index, Decoder] : enumerate(Decoders)) {
-      emitTemplate();
+      emitTemplate(OS, SpecializedInsnType);
       OS << Indent << "DecodeStatus decodeFn" << Index << "(" << DecodeParams
          << ") {\n";
       Indent += 2;
@@ -1121,7 +1128,7 @@ void DecoderEmitter::emitDecoderFunction(formatted_raw_ostream &OS,
   }
 
   OS << Indent << "// Handling " << Decoders.size() << " cases.\n";
-  emitTemplate();
+  emitTemplate(OS, SpecializedInsnType);
   OS << Indent << "static DecodeStatus decodeToMCInst(unsigned Idx, "
      << DecodeParams << ") {\n";
   Indent += 2;
@@ -2196,12 +2203,19 @@ populateInstruction(const CodeGenTarget &Target, const Record &EncodingDef,
   return Bits.getNumBits();
 }
 
+static bool isKnownIntegralType(StringRef InsnType) {
+  static constexpr StringLiteral KnownIntegralTypes[] = {"uint16_t", "uint32_t",
+                                                         "uint64_t"};
+  return llvm::is_contained(KnownIntegralTypes, InsnType);
+}
+
 // emitFieldFromInstruction - Emit the templated helper function
 // fieldFromInstruction().
 // On Windows we make sure that this function is not inlined when
 // using the VS compiler. It has a bug which causes the function
 // to be optimized out in some circumstances. See llvm.org/pr38292
-static void emitFieldFromInstruction(formatted_raw_ostream &OS) {
+static void emitFieldFromInstruction(formatted_raw_ostream &OS,
+                                     StringRef SpecializedInsnType) {
   OS << R"(
 // Helper functions for extracting fields from encoded instructions.
 // InsnType must either be integral or an APInt-like object that must:
@@ -2212,54 +2226,122 @@ static void emitFieldFromInstruction(formatted_raw_ostream &OS) {
 // * Support the ~, &, ==, and != operators with other objects of the same type
 // * Support the != and bitwise & with uint64_t
 // * Support put (<<) to raw_ostream&
-template <typename InsnType>
+
+// Helper macro to disable inlining of `fieldFromInstruction`.
 #if defined(_MSC_VER) && !defined(__clang__)
-__declspec(noinline)
+#define DEC_EMIT_NO_INLINE __declspec(noinline)
+#else
+#define DEC_EMIT_NO_INLINE
 #endif
-static std::enable_if_t<std::is_integral<InsnType>::value, InsnType>
-fieldFromInstruction(const InsnType &insn, unsigned startBit,
-                     unsigned numBits) {
+
+)";
+  StringRef InsnType = getInsnType(SpecializedInsnType);
+
+  // If InsnType is not a template type argument, we cannot use std::enable_if_t
+  // to enable or disable one of the versions of `fieldFromInstruction`. Use a
+  // set if pre-defined strings to detect which version of
+  // `fieldFromInstruction` to emit.
+  bool IsIntegralType = isKnownIntegralType(InsnType);
+  bool GenerateTemplatedForm = SpecializedInsnType.empty();
+
+  if (GenerateTemplatedForm || IsIntegralType) {
+    if (GenerateTemplatedForm) {
+      emitTemplate(OS, SpecializedInsnType);
+      OS << formatv("DEC_EMIT_NO_INLINE static "
+                    "std::enable_if_t<std::is_integral<{0}>::value, {0}>\n",
+                    InsnType);
+    } else {
+      OS << formatv("DEC_EMIT_NO_INLINE static {} ", InsnType);
+    }
+
+    OS << formatv(
+        R"(fieldFromInstruction(const {0} &insn, unsigned startBit, unsigned numBits) {{
   assert(startBit + numBits <= 64 && "Cannot support >64-bit extractions!");
-  assert(startBit + numBits <= (sizeof(InsnType) * 8) &&
+  assert(startBit + numBits <= (sizeof({0}) * 8) &&
          "Instruction field out of bounds!");
-  InsnType fieldMask;
-  if (numBits == sizeof(InsnType) * 8)
-    fieldMask = (InsnType)(-1LL);
+  {0} fieldMask;
+  if (numBits == sizeof({0}) * 8)
+    fieldMask = ({0})(-1LL);
   else
-    fieldMask = (((InsnType)1 << numBits) - 1) << startBit;
+    fieldMask = ((({0})1 << numBits) - 1) << startBit;
   return (insn & fieldMask) >> startBit;
 }
 
-template <typename InsnType>
-static std::enable_if_t<!std::is_integral<InsnType>::value, uint64_t>
-fieldFromInstruction(const InsnType &insn, unsigned startBit,
-                     unsigned numBits) {
+)",
+        InsnType);
+  } // if (GenerateTemplatedForm || IsIntegralType) {
+
+  if (GenerateTemplatedForm || !IsIntegralType) {
+    if (GenerateTemplatedForm) {
+      emitTemplate(OS, SpecializedInsnType);
+      OS << formatv(
+          "static std::enable_if_t<!std::is_integral<{0}>::value, uint64_t>\n",
+          InsnType);
+    } else {
+      OS << formatv("static uint64_t ");
+    }
+
+    OS << formatv(R"(fieldFromInstruction(const {0} &insn, unsigned startBit,
+                     unsigned numBits) {{
   return insn.extractBitsAsZExtValue(numBits, startBit);
 }
-)";
+)",
+                  InsnType);
+  } // if (GenerateTemplatedForm || !IsIntegralType)
+  OS << "#undef DEC_EMIT_NO_INLINE\n";
 }
 
 // emitInsertBits - Emit the templated helper function insertBits().
-static void emitInsertBits(formatted_raw_ostream &OS) {
+static void emitInsertBits(formatted_raw_ostream &OS,
+                           StringRef SpecializedInsnType) {
+  bool GenerateTemplatedForm = SpecializedInsnType.empty();
+  StringRef InsnType = getInsnType(SpecializedInsnType);
+  bool IsIntegralType = isKnownIntegralType(InsnType);
+
+  auto FuncDecl = formatv(R"([[maybe_unused]]
+static void insertBits({0} &field, {0} bits, unsigned startBit,
+                       unsigned numBits) {{)",
+                          InsnType);
+
   OS << R"(
 // Helper function for inserting bits extracted from an encoded instruction into
 // a field.
-template <typename InsnType>
-static void insertBits(InsnType &field, InsnType bits, unsigned startBit,
-                       unsigned numBits) {
-  if constexpr (std::is_integral<InsnType>::value) {
+)";
+  if (GenerateTemplatedForm) {
+    emitTemplate(OS, SpecializedInsnType);
+    OS << FuncDecl;
+    OS << formatv(R"(
+  if constexpr (std::is_integral<{0}>::value) {{
     assert(startBit + numBits <= sizeof field * 8);
     (void)numBits;
-    field |= (InsnType)bits << startBit;
-  } else {
+    field |= ({0})bits << startBit;
+  } else {{
     field.insertBits(bits, startBit, numBits);
   }
 }
+)",
+                  InsnType);
+  } else if (IsIntegralType) {
+    OS << FuncDecl;
+    OS << formatv(R"(
+  assert(startBit + numBits <= sizeof field * 8);
+  (void)numBits;
+  field |= ({0})bits << startBit;
+}
+)",
+                  InsnType);
+  } else {
+    // Code for !IsIntegralType
+    OS << FuncDecl;
+    OS << R"(
+  field.insertBits(bits, startBit, numBits);
+}
 )";
+  }
+  OS << '\n';
 }
 
-// emitDecodeInstruction - Emit the templated helper function
-// decodeInstruction().
+// emitDecodeInstruction - Emit the entry function function decodeInstruction().
 static void emitDecodeInstruction(formatted_raw_ostream &OS, bool IsVarLenInst,
                                   unsigned OpcodeMask,
                                   StringRef SpecializedInsnType) {
@@ -2270,29 +2352,19 @@ static void emitDecodeInstruction(formatted_raw_ostream &OS, bool IsVarLenInst,
       ((1 << MCD::OPC_CheckPredicate) | (1 << MCD::OPC_CheckPredicateOrFail));
   const bool HasSoftFail = OpcodeMask & (1 << MCD::OPC_SoftFail);
 
-  auto emitTemplate = [&OS, SpecializedInsnType] {
-    if (SpecializedInsnType.empty())
-      OS << "template <typename InsnType>\n";
-  };
-
-  StringRef InsnType =
-      SpecializedInsnType.empty() ? "InsnType" : SpecializedInsnType;
+  StringRef InsnType = getInsnType(SpecializedInsnType);
 
-  OS << R"(
-static unsigned decodeNumToSkip(const uint8_t *&Ptr) {
-  unsigned NumToSkip = *Ptr++;
-  NumToSkip |= (*Ptr++) << 8;
-)";
-  if (getNumToSkipInBytes() == 3)
-    OS << "  NumToSkip |= (*Ptr++) << 16;\n";
-  OS << R"(  return NumToSkip;
-})";
-
-  emitTemplate();
+  emitTemplate(OS, SpecializedInsnType);
   OS << R"(
 static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI, )";
-  OS << InsnType << " insn,\n";
-  OS << R"(                             uint64_t Address,
+  // For variable length instructions, use a non-const reference to match the
+  // signature of the `makeUp` function passed in.
+  if (IsVarLenInst)
+    OS << InsnType << " &insn,";
+  else
+    OS << "const " << InsnType << " &insn,";
+  OS << R"(
+                                      uint64_t Address,
                                       const MCDisassembler *DisAsm,
                                       const MCSubtargetInfo &STI)";
   if (IsVarLenInst) {
@@ -2496,16 +2568,31 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI, )
 )";
 }
 
+static void emitCommonFunctions(formatted_raw_ostream &OS) {
+  OS << R"(
 // Helper to propagate SoftFail status. Returns false if the status is Fail;
 // callers are expected to early-exit in that condition. (Note, the '&' operator
 // is correct to propagate the values of this enum; see comment on 'enum
 // DecodeStatus'.)
-static void emitCheck(formatted_raw_ostream &OS) {
-  OS << R"(
 static bool Check(DecodeStatus &Out, DecodeStatus In) {
   Out = static_cast<DecodeStatus>(Out & In);
   return Out != MCDisassembler::Fail;
 }
+)";
+
+  OS << R"(
+// Helper to decode the `NumToSkip` value encoded in the decoder table.
+static unsigned decodeNumToSkip(const uint8_t *&Ptr) {
+  unsigned NumToSkip = *Ptr++;
+  NumToSkip |= (*Ptr++) << 8;
+)";
+  if (getNumToSkipInBytes() == 3)
+    OS << "  NumToSkip |= (*Ptr++) << 16;\n";
+  OS << R"(  return NumToSkip;
+}
+
+// Forward declaration.
+[[maybe_unused]] static bool checkDecoderPredicate(unsigned Idx, const FeatureBitset &Bits);
 
 )";
 }
@@ -2575,39 +2662,36 @@ DecoderEmitter::parseNonTemplatedInsnTypes(BitwidthSet &InstrBitwidths) {
   SmallVector<NonTemplatedInsnType> Parsed;
 
   const Record *InstructionSet = Target.getInstructionSet();
-  std::vector<StringRef> InsnCPPTypes =
-      InstructionSet->getValueAsListOfStrings("InsnCPPTypes");
-
-  if (InsnCPPTypes.empty()) {
-    // If no `InsnCPPTypes` is specified in the instruction info,
-    // create a type-spec with empty values, which will trigger generation of
-    // a templated `decodeToMCInst`.
-    Parsed.emplace_back();
+  std::vector<const Record *> DecoderOptions =
+      InstructionSet->getValueAsListOfDefs("DecoderOptions");
+
+  if (DecoderOptions.empty()) {
+    // If no `DecoderOptions` is specified in the instruction info, create one
+    // with empty values, which will trigger generation of a template code.
+    Parsed.emplace_back(StringRef(""), BitwidthSet{});
     return Parsed;
   }
 
-  // Use field locations for error reporting.
-  SMLoc CPPTypesLoc = InstructionSet->getFieldLoc("InsnCPPTypes");
-  SMLoc BitwidthsLoc = InstructionSet->getFieldLoc("InsnBitwidths");
-
-  const ListInit *InsnBitwidths =
-      InstructionSet->getValueAsListInit("InsnBitwidths");
-
-  Parsed.reserve(InsnCPPTypes.size());
+  Parsed.reserve(DecoderOptions.size());
   BitwidthSet OptionBitwidths;
 
-  for (const auto &[CPPType, BWL] :
-       zip_equal(InsnCPPTypes, InsnBitwidths->getElements())) {
-    BitwidthSet Bitwidths;
+  for (const Record *Option : DecoderOptions) {
+    // Use field locations for error reporting.
+    SMLoc CPPTypesLoc = Option->getFieldLoc("CPPType");
+    SMLoc BitwidthsLoc = Option->getFieldLoc("Bitwidths");
+
+    StringRef CPPType = Option->getValueAsString("CPPType");
     if (CPPType.empty())
       PrintFatalError(CPPTypesLoc,
                       "CPP Type cannot be empty in `InsnCPPTypes`");
-    const auto *BitwidthList = dyn_cast<ListInit>(BWL);
-    if (!BitwidthList || BitwidthList->empty())
+
+    const ListInit *BWL = Option->getValueAsListInit("Bitwidths");
+    if (!BWL || BWL->empty())
       PrintFatalError(BitwidthsLoc,
-                      "No bitwidths specified for InsnCPPType : " + CPPType);
+                      "No bitwidths specified for CPPType : " + CPPType);
 
-    for (int64_t Bitwidth : BitwidthList->getAsListOfInts()) {
+    BitwidthSet Bitwidths;
+    for (int64_t Bitwidth : BWL->getAsListOfInts()) {
       if (!OptionBitwidths.insert(Bitwidth).second)
         PrintFatalError(BitwidthsLoc,
                         "Bitwidth " + Twine(Bitwidth) + " already specified.");
@@ -2618,7 +2702,7 @@ DecoderEmitter::parseNonTemplatedInsnTypes(BitwidthSet &InstrBitwidths) {
       InstrBitwidths.erase(Bitwidth);
       Bitwidths.insert(Bitwidth);
     }
-    Parsed.emplace_back(NonTemplatedInsnType{CPPType, Bitwidths});
+    Parsed.emplace_back(CPPType, Bitwidths);
   }
 
   if (!InstrBitwidths.empty()) {
@@ -2648,9 +2732,7 @@ void DecoderEmitter::run(raw_ostream &o) {
 namespace {
 )";
 
-  emitFieldFromInstruction(OS);
-  emitInsertBits(OS);
-  emitCheck(OS);
+  emitCommonFunctions(OS);
 
   Target.reverseBitsForLittleEndianEncoding();
 
@@ -2700,7 +2782,7 @@ namespace {
       OpcMap;
   std::map<unsigned, std::vector<OperandInfo>> Operands;
   std::vector<unsigned> InstrLen;
-  bool IsVarLenInst = Target.hasVariableLengthEncodings();
+  const bool IsVarLenInst = Target.hasVariableLengthEncodings();
   unsigned MaxInstLen = 0;
 
   for (const auto &[NEI, NumberedEncoding] : enumerate(NumberedEncodings)) {
@@ -2743,6 +2825,12 @@ namespace {
     }
   }
 
+  // For variable instruction, we emit a instruction length table
+  // to let the decoder know how long the instructions are.
+  // You can see example usage in M68k's disassembler.
+  if (IsVarLenInst)
+    emitInstrLenTable(OS, InstrLen);
+
   // Collect all allowed Bitwidths for instructions.
   BitwidthSet InstrBitwidths;
   for (const auto &[NSAndByteSize, _] : OpcMap) {
@@ -2753,10 +2841,21 @@ namespace {
       parseNonTemplatedInsnTypes(InstrBitwidths);
 
   DecoderTableInfo TableInfo;
-  unsigned OpcodeMask = 0;
+  bool HasCheckPredicate = false;
   for (const auto &[NTType, NTBitwidths] : NonTemplatedInsnTypes) {
     // Reset the Decoders for each non-templated type.
     TableInfo.Decoders.clear();
+    unsigned OpcodeMask = 0;
+
+    if (!NTType.empty()) {
+      OS << "// ------------------------------------------------------------\n";
+      OS << "// Decoder tables and functions for bitwidths: ";
+      interleaveComma(NTBitwidths, OS);
+      OS << "\n// Using InsnType = " << NTType << '\n';
+    }
+
+    emitFieldFromInstruction(OS, NTType);
+    emitInsertBits(OS, NTType);
 
     for (const auto &[NSAndByteSize, EncodingIDs] : OpcMap) {
       const std::string &DecoderNamespace = NSAndByteSize.first;
@@ -2796,29 +2895,17 @@ namespace {
 
     // Emit the decoder function for this BitWidth.
     emitDecoderFunction(OS, TableInfo.Decoders, NTType, indent(0));
-  }
 
-  // For variable instruction, we emit a instruction length table
-  // to let the decoder know how long the instructions are.
-  // You can see example usage in M68k's disassembler.
-  if (IsVarLenInst)
-    emitInstrLenTable(OS, InstrLen);
+    HasCheckPredicate |= OpcodeMask & ((1 << MCD::OPC_CheckPredicate) |
+                                       (1 << MCD::OPC_CheckPredicateOrFail));
 
-  const bool HasCheckPredicate =
-      OpcodeMask &
-      ((1 << MCD::OPC_CheckPredicate) | (1 << MCD::OPC_CheckPredicateOrFail));
+    emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask, NTType);
+  }
 
   // Emit the predicate function.
   if (HasCheckPredicate)
     emitPredicateFunction(OS, TableInfo.Predicates, indent(0));
 
-  // Emit the main entry point for the decoder, decodeInstruction().
-  // Generate non-templated code if exactly one InsnCPPType was specified.
-  StringRef SpecializedInsnType =
-      NonTemplatedInsnTypes.size() == 1 ? NonTemplatedInsnTypes[0].CPPType : "";
-
-  emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask, SpecializedInsnType);
-
   OS << "\n} // namespace\n";
 }
 



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