[BOLT] Read .rela.dyn in static non-pie binary (#71635)

Static non-pie binary doesn't have DYNAMIC segment and BOLT skips
reading .rela.dyn section because of it. But such binaries might have
this section for example to store IFUNC relocation which is resolved
by linked-in startup files, so force reading this section for static
executables.

Author: yota9

bolt/include/bolt/Rewrite/RewriteInstance.h

@@ -430,6 +430,7 @@ class RewriteInstance {
 
   /// Common section names.
   static StringRef getEHFrameSectionName() { return ".eh_frame"; }
+  static StringRef getRelaDynSectionName() { return ".rela.dyn"; }
 
   /// An instance of the input binary we are processing, externally owned.
   llvm::object::ELFObjectFileBase *InputFile;

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -2217,6 +2217,19 @@ void RewriteInstance::processDynamicRelocations() {
   }
 
   // The rest of dynamic relocations - DT_RELA.
+  // The static executable might have .rela.dyn secion and not have PT_DYNAMIC
+  if (!DynamicRelocationsSize && BC->IsStaticExecutable) {
+    ErrorOr<BinarySection &> DynamicRelSectionOrErr =
+        BC->getUniqueSectionByName(getRelaDynSectionName());
+    if (DynamicRelSectionOrErr) {
+      DynamicRelocationsAddress = DynamicRelSectionOrErr->getAddress();
+      DynamicRelocationsSize = DynamicRelSectionOrErr->getSize();
+      const SectionRef &SectionRef = DynamicRelSectionOrErr->getSectionRef();
+      DynamicRelativeRelocationsCount = std::distance(
+          SectionRef.relocation_begin(), SectionRef.relocation_end());
+    }
+  }
+
   if (DynamicRelocationsSize > 0) {
     ErrorOr<BinarySection &> DynamicRelSectionOrErr =
         BC->getSectionForAddress(*DynamicRelocationsAddress);

bolt/test/AArch64/ifunc.c

@@ -7,6 +7,20 @@
 // RUN: llvm-bolt %t.O0.exe -o %t.O0.bolt.exe \
 // RUN:   --print-disasm --print-only=_start | \
 // RUN:   FileCheck --check-prefix=O0_CHECK %s
+// RUN: llvm-readelf -aW %t.O0.bolt.exe | \
+// RUN:   FileCheck --check-prefix=REL_CHECK %s
+
+// Non-pie static executable doesn't generate PT_DYNAMIC, check relocation
+// is readed successfully and IPLT trampoline has been identified by bolt.
+// RUN: %clang %cflags -nostdlib -O3 %s -fuse-ld=lld -no-pie \
+// RUN:   -o %t.O3_nopie.exe -Wl,-q
+// RUN: llvm-readelf -l %t.O3_nopie.exe | \
+// RUN:   FileCheck --check-prefix=NON_DYN_CHECK %s
+// RUN: llvm-bolt %t.O3_nopie.exe -o %t.O3_nopie.bolt.exe  \
+// RUN:   --print-disasm --print-only=_start | \
+// RUN:   FileCheck --check-prefix=O3_CHECK %s
+// RUN: llvm-readelf -aW %t.O3_nopie.bolt.exe | \
+// RUN:   FileCheck --check-prefix=REL_CHECK %s
 
 // With -O3 direct call is performed on IPLT trampoline. IPLT trampoline
 // doesn't have associated symbol. The ifunc symbol has the same address as
@@ -16,6 +30,8 @@
 // RUN: llvm-bolt %t.O3_pie.exe -o %t.O3_pie.bolt.exe  \
 // RUN:   --print-disasm --print-only=_start | \
 // RUN:   FileCheck --check-prefix=O3_CHECK %s
+// RUN: llvm-readelf -aW %t.O3_pie.bolt.exe | \
+// RUN:   FileCheck --check-prefix=REL_CHECK %s
 
 // Check that IPLT trampoline located in .plt section are normally handled by
 // BOLT. The gnu-ld linker doesn't use separate .iplt section.
@@ -24,10 +40,17 @@
 // RUN: llvm-bolt %t.iplt_O3_pie.exe -o %t.iplt_O3_pie.bolt.exe  \
 // RUN:   --print-disasm --print-only=_start  | \
 // RUN:   FileCheck --check-prefix=O3_CHECK %s
+// RUN: llvm-readelf -aW %t.iplt_O3_pie.bolt.exe | \
+// RUN:   FileCheck --check-prefix=REL_CHECK %s
+
+// NON_DYN_CHECK-NOT: DYNAMIC
 
 // O0_CHECK: adr x{{[0-9]+}}, ifoo
 // O3_CHECK: b "{{resolver_foo|ifoo}}{{.*}}@PLT"
 
+// REL_CHECK: R_AARCH64_IRELATIVE [[#%x,REL_SYMB_ADDR:]]
+// REL_CHECK: [[#REL_SYMB_ADDR]] {{.*}} FUNC {{.*}} resolver_foo
+
 static void foo() {}
 
 static void *resolver_foo(void) { return foo; }