[PATCH] D58943: [RISCV][MC] Find matching pcrel_hi fixup in more cases.

[Eli Friedman via Phabricator via llvm-commits]

efriedma created this revision.
efriedma added reviewers: apazos, lewis-revill, asb.
Herald added subscribers: jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, simoncook, johnrusso, rbar.
Herald added a project: LLVM.

If a symbol points to the end of a fragment, instead of searching for fixups in that fragment, search in the next fragment.

Fixes spurious assembler error with subtarget change next to "la" pseudo-instruction, or expanded equivalent.

Alternate proposal to fix the problem discussed in https://reviews.llvm.org/D58759.


Repository:
  rL LLVM

https://reviews.llvm.org/D58943

Files:
  lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
  test/MC/RISCV/option-mix.s


Index: test/MC/RISCV/option-mix.s
===================================================================
--- /dev/null
+++ test/MC/RISCV/option-mix.s
@@ -0,0 +1,51 @@
+# RUN: llvm-mc %s -triple=riscv32 | FileCheck -check-prefix=ASM %s
+# RUN: llvm-mc %s -triple=riscv64 | FileCheck -check-prefix=ASM %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 < %s \
+# RUN:   | llvm-objdump -d -riscv-no-aliases - | FileCheck -check-prefix=DISASM %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 < %s \
+# RUN:   | llvm-objdump -d -riscv-no-aliases - | FileCheck -check-prefix=DISASM %s
+
+# Checks change of options does not cause error: could not find corresponding %pcrel_hi 
+# when assembling pseudoinstruction and its extended form.
+
+.option push
+.option norelax
+  la a0, a_symbol
+.option pop
+  la a1, another_symbol
+
+# ASM: .Lpcrel_hi0:
+# ASM: auipc   a0, %pcrel_hi(a_symbol)
+# ASM: addi    a0, a0, %pcrel_lo(.Lpcrel_hi0)
+# ASM: .Lpcrel_hi1:
+# ASM: auipc   a1, %pcrel_hi(another_symbol)
+# ASM: addi    a1, a1, %pcrel_lo(.Lpcrel_hi1)
+
+# DISASM: .Lpcrel_hi0:
+# DISASM: auipc   a0, 0
+# DISASM: addi    a0, a0, 0
+# DISASM:.Lpcrel_hi1:
+# DISASM: auipc   a1, 0
+# DISASM: addi    a1, a1, 0
+
+.option push
+.option norelax
+1:auipc   a0, %pcrel_hi(a_symbol)
+  addi    a0, a0, %pcrel_lo(1b)
+.option pop
+2:auipc   a1, %pcrel_hi(another_symbol)
+  addi    a1, a1, %pcrel_lo(2b)
+
+# ASM: .Ltmp0:
+# ASM: auipc   a0, %pcrel_hi(a_symbol)
+# ASM: addi    a0, a0, %pcrel_lo(.Ltmp0)
+# ASM: .Ltmp1:
+# ASM: auipc   a1, %pcrel_hi(another_symbol)
+# ASM: addi    a1, a1, %pcrel_lo(.Ltmp1)
+
+# DISASM: .Ltmp0:
+# DISASM: auipc   a0, 0
+# DISASM: addi    a0, a0, 0
+# DISASM: .Ltmp1:
+# DISASM: auipc   a1, 0
+# DISASM: addi    a1, a1, 0
Index: lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
===================================================================
--- lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
+++ lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
@@ -49,14 +49,22 @@
   if (!AUIPCSRE)
     return nullptr;
 
-  const auto *DF =
-      dyn_cast_or_null<MCDataFragment>(AUIPCSRE->findAssociatedFragment());
+  const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol();
+  const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment());
+
   if (!DF)
     return nullptr;
 
-  const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol();
+  uint64_t Offset = AUIPCSymbol->getOffset();
+  if (DF->getContents().size() == Offset) {
+    DF = dyn_cast_or_null<MCDataFragment>(DF->getNextNode());
+    if (!DF)
+      return nullptr;
+    Offset = 0;
+  }
+
   for (const MCFixup &F : DF->getFixups()) {
-    if (F.getOffset() != AUIPCSymbol->getOffset())
+    if (F.getOffset() != Offset)
       continue;
 
     switch ((unsigned)F.getKind()) {


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