Improve comments for r211040

Added comment to clarify why we r211040 choose to bail out of fast isel instead
of generating a more complicated relocation, and fix mislabelled register in the
comments of the asan test case.

llvm-svn: 211052

2 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index 4b8a8362c5a..e490c274b5f 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -2709,7 +2709,10 @@ unsigned X86FastISel::TargetMaterializeConstant(const Constant *C) {
 
   // Materialize addresses with LEA instructions.
   if (isa<GlobalValue>(C)) {
-    //LEA can only handle 32 bit immediates
+    // LEA can only handle 32 bit immediates. Currently this happens pretty
+    // rarely, so rather than deal with it just bail out of fast isel. If any
+    // architectures endis up needing to use this path a lot then fast isel
+    // could get the address with a MOV64ri and use that to load the value.
     if (TM.getRelocationModel() == Reloc::Static && Subtarget->is64Bit())
       return false;
 
diff --git a/llvm/test/DebugInfo/X86/debug-loc-asan.ll b/llvm/test/DebugInfo/X86/debug-loc-asan.ll
index 8730cf9d361..0e02c678717 100644
--- a/llvm/test/DebugInfo/X86/debug-loc-asan.ll
+++ b/llvm/test/DebugInfo/X86/debug-loc-asan.ll
@@ -9,7 +9,7 @@
 ; }
 ; with "clang++ -S -emit-llvm -fsanitize=address -O0 -g test.cc"
 
-; First, argument variable "y" resides in %rdi:
+; First, argument variable "y" resides in %rdx:
 ; CHECK: DEBUG_VALUE: bar:y <- RDX
 
 ; Then its address is stored in a location on a stack:
@@ -21,7 +21,7 @@
 ; CHECK: .Ldebug_loc{{[0-9]+}}:
 ; We expect two location ranges for the variable.
 
-; First, it is stored in %rdi:
+; First, it is stored in %rdx:
 ; CHECK:      .Lset{{[0-9]+}} = .Lfunc_begin0-.Lfunc_begin0
 ; CHECK-NEXT: .quad .Lset{{[0-9]+}}
 ; CHECK-NEXT: .Lset{{[0-9]+}} = [[START_LABEL]]-.Lfunc_begin0