[RISCV] Vendor Relocations for Xqci extension

llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "RISCVAsmBackend.h"
+#include "RISCVFixupKinds.h"
 #include "RISCVMCExpr.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/MC/MCAsmInfo.h"
@@ -611,6 +612,46 @@ bool RISCVAsmBackend::evaluateTargetFixup(const MCFixup &Fixup,
          isPCRelFixupResolved(AUIPCTarget.getAddSym(), *AUIPCDF);
 }
 
+void RISCVAsmBackend::maybeAddVendorReloc(const MCFragment &F,
+                                          const MCFixup &Fixup) {
+  StringRef VendorIdentifier;
+  switch (Fixup.getTargetKind()) {
+  default:
+    // No Vendor Relocation Required.
+    return;
+  case RISCV::fixup_riscv_qc_e_branch:
+  case RISCV::fixup_riscv_qc_abs20_u:
+  case RISCV::fixup_riscv_qc_e_32:
+  case RISCV::fixup_riscv_qc_e_jump_plt:
+    VendorIdentifier = "QUALCOMM";
+    break;
+  }
+
+  // Create a local symbol for the vendor relocation to reference. It's fine if
+  // the symbol has the same name as an existing symbol.
+  MCContext &Ctx = Asm->getContext();
+  MCSymbol *VendorSymbol = Ctx.createLocalSymbol(VendorIdentifier);
+  auto [It, Inserted] =
+      VendorSymbols.try_emplace(VendorIdentifier, VendorSymbol);
+
+  if (Inserted) {
+    // Setup the just-created symbol
+    VendorSymbol->setVariableValue(MCConstantExpr::create(0, Ctx));
+    Asm->registerSymbol(*VendorSymbol);
+  } else {
+    // Fetch the existing symbol
+    VendorSymbol = It->getValue();
+  }
+
+  MCFixup VendorFixup =
+      MCFixup::create(Fixup.getOffset(), nullptr, ELF::R_RISCV_VENDOR);
+  // Explicitly create MCValue rather than using an MCExpr and evaluating it so
+  // that the absolute vendor symbol is not evaluated to constant 0.
+  MCValue VendorTarget = MCValue::get(VendorSymbol);
+  uint64_t VendorValue;
+  Asm->getWriter().recordRelocation(F, VendorFixup, VendorTarget, VendorValue);
+}
+
 bool RISCVAsmBackend::addReloc(const MCFragment &F, const MCFixup &Fixup,
                                const MCValue &Target, uint64_t &FixedValue,
                                bool IsResolved) {
@@ -660,7 +701,14 @@ bool RISCVAsmBackend::addReloc(const MCFragment &F, const MCFixup &Fixup,
   if (IsResolved &&
       (getFixupKindInfo(Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel))
     IsResolved = isPCRelFixupResolved(Target.getAddSym(), F);
-  IsResolved = MCAsmBackend::addReloc(F, Fixup, Target, FixedValue, IsResolved);
+
+  if (!IsResolved) {
+    // Some Fixups require a vendor relocation, record it (directly) before we
+    // add the relocation.
+    maybeAddVendorReloc(F, Fixup);
+
+    Asm->getWriter().recordRelocation(F, Fixup, Target, FixedValue);
+  }
 
   if (Fixup.isLinkerRelaxable()) {
     auto FA = MCFixup::create(Fixup.getOffset(), nullptr, ELF::R_RISCV_RELAX);

llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.h

@@ -12,6 +12,7 @@
 #include "MCTargetDesc/RISCVBaseInfo.h"
 #include "MCTargetDesc/RISCVFixupKinds.h"
 #include "MCTargetDesc/RISCVMCTargetDesc.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCFixupKindInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
@@ -31,6 +32,8 @@ class RISCVAsmBackend : public MCAsmBackend {
 
   bool isPCRelFixupResolved(const MCSymbol *SymA, const MCFragment &F);
 
+  StringMap<MCSymbol *> VendorSymbols;
+
 public:
   RISCVAsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI, bool Is64Bit,
                   const MCTargetOptions &Options);
@@ -50,6 +53,8 @@ class RISCVAsmBackend : public MCAsmBackend {
   bool addReloc(const MCFragment &, const MCFixup &, const MCValue &,
                 uint64_t &FixedValue, bool IsResolved) override;
 
+  void maybeAddVendorReloc(const MCFragment &, const MCFixup &);
+
   void applyFixup(const MCFragment &, const MCFixup &, const MCValue &Target,
                   MutableArrayRef<char> Data, uint64_t Value,
                   bool IsResolved) override;

llvm/test/MC/RISCV/vendor-symbol.s

@@ -0,0 +1,35 @@
+# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcibi %s \
+# RUN:     -filetype=obj -o - \
+# RUN:     | llvm-readelf -sr - \
+# RUN:     | FileCheck %s
+
+
+## This checks that the vendor identifier symbols required for vendor
+## relocations do not interfere with symbols with identical names that
+## are written in assembly.
+
+  .option exact
+
+  qc.e.bgeui s0, 20, QUALCOMM
+
+  .global QUALCOMM
+QUALCOMM:
+  nop
+
+  qc.e.bgeui s0, 20, QUALCOMM
+
+
+# CHECK-LABEL: Relocation section '.rela.text'
+## Note the different values for the "Sym. Value" Field
+# CHECK: R_RISCV_VENDOR    00000000 QUALCOMM + 0
+# CHECK: R_RISCV_CUSTOM193 00000006 QUALCOMM + 0
+# CHECK: R_RISCV_VENDOR    00000000 QUALCOMM + 0
+# CHECK: R_RISCV_CUSTOM193 00000006 QUALCOMM + 0
+
+
+# CHECK-LABEL: Symbol table '.symtab'
+# CHECK-NOT: QUALCOMM
+# CHECK: 00000000 0 NOTYPE  LOCAL  DEFAULT ABS QUALCOMM
+# CHECK-NOT: QUALCOMM
+# CHECK: 00000006 0 NOTYPE  GLOBAL DEFAULT   2 QUALCOMM
+# CHECK-NOT: QUALCOMM

llvm/test/MC/RISCV/xqcibi-relocations.s

@@ -1,38 +1,83 @@
-# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcibi %s -show-encoding \
-# RUN:     | FileCheck -check-prefix=INSTR %s
-# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+experimental-xqcibi %s -o %t.o
-# RUN: llvm-readobj -r %t.o | FileCheck -check-prefix=RELOC %s
+# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcibi %s \
+# RUN:     | FileCheck -check-prefix=ASM %s
+# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcibi %s \
+# RUN:     -filetype=obj -o - \
+# RUN:     | llvm-objdump -dr --mattr=+experimental-xqcibi - \
+# RUN:     | FileCheck -check-prefix=OBJ %s
 
-# Check prefixes:
-# RELOC - Check the relocation in the object.
-# INSTR - Check the instruction is handled properly by the ASMPrinter.
+## This test checks that we emit the right relocations for Xqcibi
+## relative branches. These can be resolved within the same section
+## (when relaxations are disabled) but otherwise require a relocation.
+## The QC.E.B<op>I instructions also require a vendor relocation.
 
-.text
+# This is required so that the conditional branches requiring relocations
+# are not converted into inverted branches with long jumps by the assembler.
+.option exact
 
-# Since foo is undefined, this will be relaxed to (qc.beqi + jal)
-qc.bnei x6, 10, foo
-# RELOC: R_RISCV_JAL foo 0x0
-# INSTR: qc.bnei t1, 10, foo
+# ASM-LABEL: this_section:
+# OBJ-LABEL: <this_section>:
+this_section:
 
-# Since foo is undefined, this will be relaxed to (qc.e.bltui + jal)
-qc.e.bgeui x8, 12, foo
-# RELOC: R_RISCV_JAL foo 0x0
-# INSTR: qc.e.bgeui s0, 12, foo
+# ASM: qc.bnei t1, 10, undef
+# OBJ: qc.bnei t1, 0xa, 0x0 <this_section>
+# OBJ-NEXT: R_RISCV_BRANCH undef{{$}}
+qc.bnei t1, 10, undef
 
-# Check that a label in a different section is handled similar to an undefined
-# symbol and gets relaxed to (qc.e.bgeui + jal)
-qc.e.bltui x4, 9, .bar
-# RELOC: R_RISCV_JAL .bar 0x0
-# INSTR: qc.e.bltui tp, 9, .bar
+# ASM: qc.e.bgeui s0, 20, undef
+# OBJ-NEXT: qc.e.bgeui s0, 0x14, 0x4 <this_section+0x4>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM193 undef{{$}}
+qc.e.bgeui s0, 20, undef
 
-# Check that branches to a defined symbol are handled correctly
-qc.e.beqi x7, 8, .L1
-# INSTR: qc.e.beqi t2, 8, .L1
 
-.L1:
-  ret
+# ASM: qc.bnei t2, 11, same_section
+# OBJ-NEXT: qc.bnei t2, 0xb, 0x28 <same_section>
+qc.bnei t2, 11, same_section
 
-.section .t2
+# ASM: qc.e.bgeui s1, 21, same_section
+# OBJ-NEXT: qc.e.bgeui s1, 0x15, 0x28 <same_section>
+qc.e.bgeui s1, 21, same_section
 
-.bar:
-  ret
+
+# ASM: qc.bnei t2, 12, same_section_extern
+# OBJ-NEXT: qc.bnei t2, 0xc, 0x14 <this_section+0x14>
+# OBJ-NEXT: R_RISCV_BRANCH same_section_extern{{$}}
+qc.bnei t2, 12, same_section_extern
+
+# ASM: qc.e.bgeui s1, 22, same_section_extern
+# OBJ-NEXT: qc.e.bgeui s1, 0x16, 0x18 <this_section+0x18>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM193 same_section_extern{{$}}
+qc.e.bgeui s1, 22, same_section_extern
+
+
+# ASM: qc.bnei t3, 13, other_section
+# OBJ-NEXT: qc.bnei t3, 0xd, 0x1e <this_section+0x1e>
+# OBJ-NEXT: R_RISCV_BRANCH other_section{{$}}
+qc.bnei t3, 13, other_section
+
+# ASM: qc.e.bgeui s2, 23, other_section
+# OBJ-NEXT: qc.e.bgeui s2, 0x17, 0x22 <this_section+0x22>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM193 other_section{{$}}
+qc.e.bgeui s2, 23, other_section
+
+
+# ASM-LABEL: same_section:
+# OBJ-LABEL: <same_section>:
+same_section:
+  nop
+
+# ASM-LABEL: same_section_extern:
+# OBJ-LABEL: <same_section_extern>:
+  .global same_section_extern
+same_section_extern:
+  nop
+
+
+.section .text.second, "ax", @progbits
+
+# ASM-LABEL: other_section:
+# OBJ-LABEL: <other_section>:
+other_section:
+  nop

llvm/test/MC/RISCV/xqcilb-relocations.s

@@ -1,46 +1,84 @@
-# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcilb %s -show-encoding \
-# RUN:     | FileCheck -check-prefix=INSTR %s
-# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+experimental-xqcilb %s -o %t.o
-# RUN: llvm-readobj -r %t.o | FileCheck -check-prefix=RELOC %s
+# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcilb %s \
+# RUN:     | FileCheck -check-prefix=ASM %s
+# RUN: llvm-mc -triple riscv32 -mattr=+experimental-xqcilb %s \
+# RUN:     -filetype=obj -o - \
+# RUN:     | llvm-objdump -dr --mattr=+experimental-xqcilb - \
+# RUN:     | FileCheck -check-prefix=OBJ %s
 
-# Check prefixes:
-# RELOC - Check the relocation in the object.
-# INSTR - Check the instruction is handled properly by the ASMPrinter.
-
-.text
+## This test checks that we emit the right relocations for Xqcilb
+## relative jumps. These can be resolved within the same section
+## (when relaxations are disabled) but otherwise require a
+## vendor-specific relocation pair.
 
+# This is required so that the conditional jumps are not compressed
+# by the assembler
 .option exact
 
-qc.e.j foo
-# RELOC: R_RISCV_CUSTOM195 foo 0x0
-# INSTR: qc.e.j foo
+# ASM-LABEL: this_section:
+# OBJ-LABEL: <this_section>:
+this_section:
+
+# ASM: qc.e.j undef
+# OBJ: qc.e.j 0x0 <this_section>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 undef{{$}}
+qc.e.j undef
+
+# ASM: qc.e.jal undef
+# OBJ-NEXT: qc.e.jal 0x6 <this_section+0x6>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 undef{{$}}
+qc.e.jal undef
+
+
+# ASM: qc.e.j same_section
+# OBJ-NEXT: qc.e.j 0x30 <same_section>
+qc.e.j same_section
+
+# ASM: qc.e.jal same_section
+# OBJ-NEXT: qc.e.jal 0x30 <same_section>
+qc.e.jal same_section
+
+# ASM: qc.e.j same_section_extern
+# OBJ-NEXT: qc.e.j 0x18 <this_section+0x18>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 same_section_extern{{$}}
+qc.e.j same_section_extern
 
-qc.e.jal foo
-# RELOC: R_RISCV_CUSTOM195 foo 0x0
-# INSTR: qc.e.jal foo
+# ASM: qc.e.jal same_section_extern
+# OBJ-NEXT: qc.e.jal 0x1e <this_section+0x1e>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 same_section_extern{{$}}
+qc.e.jal same_section_extern
 
-# Check that a label in a different section is handled similar to an undefined symbol
-qc.e.j .bar
-# RELOC: R_RISCV_CUSTOM195 .bar 0x0
-# INSTR: qc.e.j .bar
 
-qc.e.jal .bar
-# RELOC: R_RISCV_CUSTOM195 .bar 0x0
-# INSTR: qc.e.jal .bar
+# ASM: qc.e.j other_section
+# OBJ-NEXT: qc.e.j 0x24 <this_section+0x24>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 other_section{{$}}
+qc.e.j other_section
 
-# Check that jumps to a defined symbol are handled correctly
-qc.e.j .L1
-# INSTR:qc.e.j .L1
+# ASM: qc.e.jal other_section
+# OBJ-NEXT: qc.e.jal 0x2a <this_section+0x2a>
+# OBJ-NEXT: R_RISCV_VENDOR QUALCOMM{{$}}
+# OBJ-NEXT: R_RISCV_CUSTOM195 other_section{{$}}
+qc.e.jal other_section
 
-qc.e.jal .L1
-# INSTR:qc.e.jal .L1
 
-.option noexact
+# ASM-LABEL: same_section:
+# OBJ-LABEL: <same_section>:
+same_section:
+  nop
 
-.L1:
-  ret
+# ASM-LABEL: same_section_extern:
+# OBJ-LABEL: <same_section_extern>:
+  .global same_section_extern
+same_section_extern:
+  nop
 
-.section .t2
+.section .text.other, "ax", @progbits
 
-.bar:
-  ret
+# ASM-LABEL: other_section:
+# OBJ-LABEL: <other_section>:
+other_section:
+  nop