From: Lang Hames <lhames@gmail.com>
Date: Thu, 15 Oct 2015 06:41:45 +0000 (+0000)
Subject: [RuntimeDyld] Don't try to get the contents of sections that don't have any
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=9816f9eac902b84ec044bc11f6243d9e9400f3ef;hp=c770c8d638a69cd3cd527c54f08008f45bbab2c5

[RuntimeDyld] Don't try to get the contents of sections that don't have any
(e.g. bss sections).

MachO and ELF have been silently letting this pass, but COFFObjectFile contains
an assertion to catch this kind of (ab)use of the getSectionContents, and this
was causing the JIT to crash on COFF objects with BSS sections. This patch
should fix that.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250371 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index b2f017c94cb..27cd09834df 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -182,8 +182,6 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
           continue;
         uint64_t SectOffset;
         Check(getOffset(*I, *SI, SectOffset));
-        StringRef SectionData;
-        Check(SI->getContents(SectionData));
         bool IsCode = SI->isText();
         unsigned SectionID =
             findOrEmitSection(Obj, *SI, IsCode, LocalSections);
@@ -568,12 +566,14 @@ unsigned RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
   uint8_t *Addr;
   const char *pData = nullptr;
 
-  // In either case, set the location of the unrelocated section in memory,
-  // since we still process relocations for it even if we're not applying them.
-  Check(Section.getContents(data));
-  // Virtual sections have no data in the object image, so leave pData = 0
-  if (!IsVirtual)
+  // If this section contains any bits (i.e. isn't a virtual or bss section),
+  // grab a reference to them.
+  if (!IsVirtual && !IsZeroInit) {
+    // In either case, set the location of the unrelocated section in memory,
+    // since we still process relocations for it even if we're not applying them.
+    Check(Section.getContents(data));
     pData = data.data();
+  }
 
   // Code section alignment needs to be at least as high as stub alignment or
   // padding calculations may by incorrect when the section is remapped to a
diff --git a/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64 b/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64
deleted file mode 100644
index 7029cf437c5..00000000000
--- a/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64
+++ /dev/null
@@ -1,31 +0,0 @@
-# RUN: llvm-mc -triple=x86_64-pc-win32 -filetype=obj -o %T/COFF_x86_64.o %s
-# RUN: llvm-rtdyld -triple=x86_64-pc-win32 -verify -check=%s %/T/COFF_x86_64.o
-        	.text
-	.def	 F;
-	.scl	2;
-	.type	32;
-	.endef
-	.globl	__real400921f9f01b866e
-	.section	.rdata,"dr",discard,__real400921f9f01b866e
-	.align	8
-__real400921f9f01b866e:
-	.quad	4614256650576692846     # double 3.1415899999999999
-	.text
-	.globl	F
-        .global inst1
-	.align	16, 0x90
-F:                                      # @F
-.Ltmp0:
-.seh_proc F
-# BB#0:                                 # %entry
-.Ltmp1:
-	.seh_endprologue
-# rtdyld-check: decode_operand(inst1, 4) = __real400921f9f01b866e - next_pc(inst1)
-inst1:
-	movsd	__real400921f9f01b866e(%rip), %xmm0 # xmm0 = mem[0],zero
-	retq
-.Leh_func_end0:
-.Ltmp2:
-	.seh_endproc
-
-
diff --git a/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64.s b/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64.s
new file mode 100644
index 00000000000..fc0f3e85147
--- /dev/null
+++ b/test/ExecutionEngine/RuntimeDyld/X86/COFF_x86_64.s
@@ -0,0 +1,34 @@
+# RUN: llvm-mc -triple=x86_64-pc-win32 -filetype=obj -o %T/COFF_x86_64.o %s
+# RUN: llvm-rtdyld -triple=x86_64-pc-win32 -verify -check=%s %/T/COFF_x86_64.o
+        	.text
+	.def	 F;
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	__real400921f9f01b866e
+	.section	.rdata,"dr",discard,__real400921f9f01b866e
+	.align	8
+__real400921f9f01b866e:
+	.quad	4614256650576692846     # double 3.1415899999999999
+	.text
+	.globl	F
+        .global inst1
+	.align	16, 0x90
+F:                                      # @F
+.Ltmp0:
+.seh_proc F
+# BB#0:                                 # %entry
+.Ltmp1:
+	.seh_endprologue
+# rtdyld-check: decode_operand(inst1, 4) = __real400921f9f01b866e - next_pc(inst1)
+inst1:
+	movsd	__real400921f9f01b866e(%rip), %xmm0 # xmm0 = mem[0],zero
+	retq
+.Leh_func_end0:
+.Ltmp2:
+	.seh_endproc
+
+# Make sure the JIT doesn't bail out on BSS sections.
+        .bss
+bss_check:
+        .fill 8, 1, 0