[RISCV] Generate address sequences suitable for mcmodel=medium

This patch adds an implementation of a PC-relative addressing sequence to be
used when -mcmodel=medium is specified. With absolute addressing, a 'medium'
codemodel may cause addresses to be out of range. This is because while
'medium' implies a 2 GiB addressing range, this 2 GiB can be at any offset as
opposed to 'small', which implies the first 2 GiB only.

Note that LLVM/Clang currently specifies code models differently to GCC, where
small and medium imply the same functionality as GCC's medlow and medany
respectively.

Differential Revision: https://reviews.llvm.org/D54143
Patch by Lewis Revill.

llvm-svn: 357393

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index f467c390a66..cbdd46384a7 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2925,13 +2925,16 @@ void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock &MBB) const {
 
   // Print the main label for the block.
   if (MBB.pred_empty() ||
-      (isBlockOnlyReachableByFallthrough(&MBB) && !MBB.isEHFuncletEntry())) {
+      (isBlockOnlyReachableByFallthrough(&MBB) && !MBB.isEHFuncletEntry() &&
+       !MBB.hasLabelMustBeEmitted())) {
     if (isVerbose()) {
       // NOTE: Want this comment at start of line, don't emit with AddComment.
       OutStreamer->emitRawComment(" %bb." + Twine(MBB.getNumber()) + ":",
                                   false);
     }
   } else {
+    if (isVerbose() && MBB.hasLabelMustBeEmitted())
+      OutStreamer->AddComment("Label of block must be emitted");
     OutStreamer->EmitLabel(MBB.getSymbol());
   }
 }