Reflect the result of code-shrinking relaxation to symbol sizes

rui314 · Jan 5, 2025 · e6345d5 · e6345d5
1 parent ba35344
commit e6345d5
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Showing 3 changed files with 43 additions and 2 deletions.
diff --git a/src/mold.h b/src/mold.h
@@ -269,7 +269,7 @@ struct InputSectionExtras<E> {
   std::vector<RelocDelta> r_deltas;
 };
 
-static i64 get_removed_bytes(std::span<RelocDelta> deltas, i64 i) {
+inline i64 get_removed_bytes(std::span<RelocDelta> deltas, i64 i) {
   if (i == 0)
     return deltas[i].delta;
   return deltas[i].delta - deltas[i - 1].delta;

diff --git a/src/output-chunks.cc b/src/output-chunks.cc
@@ -1751,6 +1751,19 @@ void RelPltSection<E>::copy_buf(Context<E> &ctx) {
   }
 }
 
+// RISC-V and LoongArch have code-shrinking linker relaxation. If we
+// have removed instructions from a function, we need to update its
+// size as well.
+template <typename E>
+static u64 get_symbol_size(Symbol<E> &sym) {
+  const ElfSym<E> &esym = sym.esym();
+  if constexpr (is_riscv<E> || is_loongarch<E>)
+    if (InputSection<E> *isec = sym.get_input_section())
+      if (!isec->extra.r_deltas.empty())
+        return esym.st_size - get_r_delta(*isec, esym.st_value + esym.st_size);
+  return esym.st_size;
+}
+
 template <typename E>
 ElfSym<E> to_output_esym(Context<E> &ctx, Symbol<E> &sym, u32 st_name,
                          U32<E> *shn_xindex) {
@@ -1759,7 +1772,7 @@ ElfSym<E> to_output_esym(Context<E> &ctx, Symbol<E> &sym, u32 st_name,
 
   esym.st_name = st_name;
   esym.st_type = sym.get_type();
-  esym.st_size = sym.esym().st_size;
+  esym.st_size = get_symbol_size(sym);
 
   if (sym.is_local(ctx))
     esym.st_bind = STB_LOCAL;

diff --git a/test/arch-riscv64-symbol-size.sh b/test/arch-riscv64-symbol-size.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+. $(dirname $0)/common.inc
+
+cat <<EOF | $CC -o $t/a.o -c -xassembler -
+.globl get_foo
+.type get_foo @function
+get_foo:
+  lui a0, %hi(foo)
+  add a0, a0, %lo(foo)
+  ret
+.size get_foo, .-get_foo
+EOF
+
+cat <<EOF | $CC -o $t/b.o -c -xassembler -
+.globl foo, bar, baz
+foo = 0xf00
+EOF
+
+cat <<EOF | $CC -o $t/c.o -c -xc -
+#include <stdio.h>
+int get_foo();
+int main() { printf("%x\n", get_foo()); }
+EOF
+
+$CC -B. -o $t/exe $t/a.o $t/b.o $t/c.o
+
+readelf --syms $t/a.o | grep -Eq ' 10 FUNC .* get_foo$'
+readelf --syms $t/exe | grep -Eq ' 8 FUNC .* get_foo$'