Add a crate for missing stubs from libcore

The core library in theory has 0 dependencies, but in practice it has some in
order for it to be efficient. These dependencies are in the form of the basic
memory operations provided by libc traditionally, such as memset, memcmp, etc.
These functions are trivial to implement and themselves have 0 dependencies.

This commit adds a new crate, librlibc, which will serve the purpose of
providing these dependencies. The crate is never linked to by default, but is
available to be linked to by downstream consumers. Normally these functions are
provided by the system libc, but in other freestanding contexts a libc may not
be available. In these cases, librlibc will suffice for enabling execution with
libcore.

cc #10116

1 files changed, 14 insertions, 4 deletions

diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index 1031f3c1570..64776421fa1 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -128,17 +128,27 @@ LLVMRustAddAnalysisPasses(LLVMTargetMachineRef TM,
 // Unfortunately, the LLVM C API doesn't provide a way to set the `LibraryInfo`
 // field of a PassManagerBuilder, we expose our own method of doing so.
 extern "C" void
-LLVMRustAddBuilderLibraryInfo(LLVMPassManagerBuilderRef PMB, LLVMModuleRef M) {
+LLVMRustAddBuilderLibraryInfo(LLVMPassManagerBuilderRef PMB,
+                              LLVMModuleRef M,
+                              bool DisableSimplifyLibCalls) {
     Triple TargetTriple(unwrap(M)->getTargetTriple());
-    unwrap(PMB)->LibraryInfo = new TargetLibraryInfo(TargetTriple);
+    TargetLibraryInfo *TLI = new TargetLibraryInfo(TargetTriple);
+    if (DisableSimplifyLibCalls)
+      TLI->disableAllFunctions();
+    unwrap(PMB)->LibraryInfo = TLI;
 }
 
 // Unfortunately, the LLVM C API doesn't provide a way to create the
 // TargetLibraryInfo pass, so we use this method to do so.
 extern "C" void
-LLVMRustAddLibraryInfo(LLVMPassManagerRef PMB, LLVMModuleRef M) {
+LLVMRustAddLibraryInfo(LLVMPassManagerRef PMB,
+                       LLVMModuleRef M,
+                       bool DisableSimplifyLibCalls) {
     Triple TargetTriple(unwrap(M)->getTargetTriple());
-    unwrap(PMB)->add(new TargetLibraryInfo(TargetTriple));
+    TargetLibraryInfo *TLI = new TargetLibraryInfo(TargetTriple);
+    if (DisableSimplifyLibCalls)
+      TLI->disableAllFunctions();
+    unwrap(PMB)->add(TLI);
 }
 
 // Unfortunately, the LLVM C API doesn't provide an easy way of iterating over