Add tests for to prevent local-global merging

llvm · pranavk · May 13, 2025 · May 13, 2025 · May 13, 2025 · May 14, 2025
commit 6c41c380415015809f8abb9befc9609b8579cc12
diff --git a/lld/ELF/ICF.cpp b/lld/ELF/ICF.cpp
@@ -618,10 +618,11 @@ template <class ELFT> void ICF<ELFT>::run() {
          getRelocTargetSyms<ELFT>(sections[i]);
      assert(syms.size() == replacedSyms.size() &&
             "Should have same number of syms!");
-      for (size_t i = 0; i < syms.size(); i++) {
-        if (!canMergeSymbols(syms[i].second, replacedSyms[i].second))
+      for (size_t j = 0; j < syms.size(); j++) {
+        if (!syms[j].first->isGlobal() || !replacedSyms[j].first->isGlobal() ||
+            !canMergeSymbols(syms[j].second, replacedSyms[j].second))
          continue;
-        symbolEquivalence.unionSets(syms[i].first, replacedSyms[i].first);
+        symbolEquivalence.unionSets(syms[j].first, replacedSyms[j].first);
      }

      // At this point we know sections merged are fully identical and hence

diff --git a/lld/test/ELF/icf-addend.s b/lld/test/ELF/icf-addend.s
@@ -2,31 +2,50 @@
 # RUN: rm -rf %t && split-file %s %t && cd %t

 #--- trivial-relocation.s
-# For trivial relocations, merging two equivalent sections is allowed but we must not
-# merge their symbols if addends are different.
+# Tests following for trivial relocations:
+# 1. Merging two equivalent sections is allowed but we must not merge their symbols if addends are different.
+# 2. Local symbols should not be merged together even though their sections can be merged together.

 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux trivial-relocation.s -o trivial.o
-# RUN: ld.lld trivial.o -o /dev/null --icf=all --print-icf-sections | FileCheck %s
+# RUN: ld.lld trivial.o -o /dev/null --icf=all --print-icf-sections | FileCheck %s --check-prefix=TRIVIAL

-# CHECK: selected section {{.*}}:(.text.f1)
-# CHECK:   removing identical section {{.*}}:(.text.f2)
-# CHECK-NOT: redirecting 'y' in symtab to x
-# CHECK-NOT: redirecting 'y' to 'x'
+# TRIVIAL: selected section {{.*}}:(.rodata.sec1)
+# TRIVIAL-NEXT:   removing identical section {{.*}}:(.rodata.sec2)
+# TRIVIAL-NEXT: selected section {{.*}}:(.text.f1)
+# TRIVIAL-NEXT:   removing identical section {{.*}}:(.text.f2)
+# TRIVIAL-NEXT:   removing identical section {{.*}}:(.text.f1_local)
+# TRIVIAL-NEXT:   removing identical section {{.*}}:(.text.f2_local)

-.globl x, y
+.addrsig

-.section .rodata,"a",@progbits
+.globl x_glob, y_glob
+
+.section .rodata.sec1,"a",@progbits
+x_glob:
+.long 11
+y_glob:
+.long 12
+
+.section .rodata.sec2,"a",@progbits
 x:
 .long 11
 y:
 .long 12

 .section .text.f1,"ax",@progbits
 f1:
-movq x+4(%rip), %rax 
+movq x_glob+4(%rip), %rax

 .section .text.f2,"ax",@progbits
 f2:
+movq y_glob(%rip), %rax
+
+.section .text.f1_local,"ax",@progbits
+f1_local:
+movq x+4(%rip), %rax
+
+.section .text.f2_local,"ax",@progbits
+f2_local:
 movq y(%rip), %rax

 .section .text._start,"ax",@progbits
@@ -36,34 +55,52 @@ call f1
 call f2

 #--- non-trivial-relocation.s
-# For non-trivial relocations, we must not merge sections if addends are different.
-# Not merging sections would automatically disable symbol merging.
+# Tests following for non-trivial relocations:
+# 1. We must not merge sections if addends are different.
+# 2. We must not merge sections pointing to local and global symbols.

-# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux trivial-relocation.s -o trivial.o
-# RUN: ld.lld trivial.o -o /dev/null --icf=all --print-icf-sections | FileCheck %s
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux non-trivial-relocation.s -o non-trivial.o
+# RUN: ld.lld non-trivial.o -o /dev/null --icf=all --print-icf-sections | FileCheck %s --check-prefix=NONTRIVIAL
+
+# NONTRIVIAL: selected section {{.*}}:(.rodata.sec1)
+# NONTRIVIAL-NEXT:   removing identical section {{.*}}:(.rodata.sec2)
+# NONTRIVIAL-NEXT: selected section {{.*}}:(.text.f1_local)
+# NONTRIVIAL-NEXT:   removing identical section {{.*}}:(.text.f2_local)

-# CHECK-NOT: selected section {{.*}}:(.text.f1)
-# CHECK-NOT:   removing identical section {{.*}}:(.text.f2)
+.addrsig

-.globl x, y
+.globl x_glob, y_glob

-.section .rodata,"a",@progbits
+.section .rodata.sec1,"a",@progbits
+x_glob:
+.long 11
+y_glob:
+.long 12
+
+.section .rodata.sec2,"a",@progbits
 x:
 .long 11
 y:
 .long 12

 .section .text.f1,"ax",@progbits
 f1:
-movq x+4@GOTPCREL(%rip), %rax
+movq x_glob+4@GOTPCREL(%rip), %rax

 .section .text.f2,"ax",@progbits
 f2:
-movq y@GOTPCREL(%rip), %rax
+movq y_glob@GOTPCREL(%rip), %rax
+
+.section .text.f1_local,"ax",@progbits
+f1_local:
+movq x+4(%rip), %rax
+
+.section .text.f2_local,"ax",@progbits
+f2_local:
+movq y(%rip), %rax

 .section .text._start,"ax",@progbits
 .globl _start
 _start:
 call f1
 call f2
-