[llvm] 01baeda - [JITLink][ELF] Handle BSS sections, improve some error messages.

[Lang Hames via llvm-commits]

Author: Lang Hames
Date: 2020-10-05T21:35:35-07:00
New Revision: 01baeda7ca6645f5d8455733b110c89203a61ccf

URL: https://github.com/llvm/llvm-project/commit/01baeda7ca6645f5d8455733b110c89203a61ccf
DIFF: https://github.com/llvm/llvm-project/commit/01baeda7ca6645f5d8455733b110c89203a61ccf.diff

LOG: [JITLink][ELF] Handle BSS sections, improve some error messages.

This patch enables basic BSS section handling, and improves a couple of error
messages in the ELF section parsing code.

Patch by Christian Schafmeister. Thanks Christian!

Differential Revision: https://reviews.llvm.org/D88867

Added: 
    

Modified: 
    llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
    llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
index 20295434d2e5..40c7d04378e5 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -357,6 +357,9 @@ class ELFLinkGraphBuilder_x86_64 {
         if (SecRef.sh_type == ELF::SHT_SYMTAB)
           // TODO: Dynamic?
           SymTab = SecRef;
+      } else {
+        auto &Section = G->createSection(*Name, Prot);
+        G->createZeroFillBlock(Section, Size, Address, Alignment, 0);
       }
     }
 
@@ -480,7 +483,8 @@ class ELFLinkGraphBuilder_x86_64 {
         return Name.takeError();
       auto Section = G->findSectionByName(*Name);
       if (!Section)
-        return make_error<llvm::StringError>("Could not find a section",
+        return make_error<llvm::StringError>("Could not find a section " +
+                                             *Name,
                                              llvm::inconvertibleErrorCode());
       // we only have one for now
       auto blocks = Section->blocks();
@@ -527,7 +531,8 @@ class ELFLinkGraphBuilder_x86_64 {
           auto JitSection = G->findSectionByName(*sectName);
           if (!JitSection)
             return make_error<llvm::StringError>(
-                "Could not find a section", llvm::inconvertibleErrorCode());
+                "Could not find the JitSection " + *sectName,
+                llvm::inconvertibleErrorCode());
           auto bs = JitSection->blocks();
           if (bs.empty())
             return make_error<llvm::StringError>(

diff  --git a/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s b/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
index ca9c926b32de..0eef11110264 100644
--- a/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
+++ b/llvm/test/ExecutionEngine/JITLink/X86/ELF_x86-64_relocations.s
@@ -46,6 +46,17 @@ named_data:
         .long   42
         .size   named_data, 4
 
+# Test BSS / zero-fill section handling.
+# llvm-jitlink: *{4}bss_variable = 0
+
+	.type	bss_variable, at object
+	.bss
+	.globl	bss_variable
+	.p2align	2
+bss_variable:
+	.long	0
+	.size	bss_variable, 4
+
         .ident  "clang version 10.0.0-4ubuntu1 "
         .section        ".note.GNU-stack","", at progbits
-        .addrsig
\ No newline at end of file
+        .addrsig