[llvm-mca] Fix PR38575: Avoid an invalid implicit truncation of a processor resource mask (an uint64_t value) to unsigned.

This patch fixes a regression introduced at revision 338702.

A processor resource mask was incorrectly implicitly truncated to an unsigned
quantity. Later on, the truncated mask was used to initialize an element of a
vector of processor resource descriptors.
On targets with more than 32 processor resources, some elements of the vector
are left uninitialized. As a consequence, this bug might have eventually caused
a crash due to null dereference in the Scheduler.

This patch fixes PR38575, and adds a test for it.

llvm-svn: 339768

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/tools/llvm-mca/Scheduler.cpp b/llvm/tools/llvm-mca/Scheduler.cpp
index 764cd23c40d..f6b70d7cdf8 100644
--- a/llvm/tools/llvm-mca/Scheduler.cpp
+++ b/llvm/tools/llvm-mca/Scheduler.cpp
@@ -59,7 +59,7 @@ void ResourceManager::initialize(const llvm::MCSchedModel &SM) {
   Resources.resize(SM.getNumProcResourceKinds());
 
   for (unsigned I = 0, E = SM.getNumProcResourceKinds(); I < E; ++I) {
-    unsigned Mask = ProcResID2Mask[I];
+    uint64_t Mask = ProcResID2Mask[I];
     Resources[getResourceStateIndex(Mask)] =
         llvm::make_unique<ResourceState>(*SM.getProcResource(I), I, Mask);
   }