Support MO_{Add,Sub}IntC and MO_Add2 in the LLVM backend

This includes:

- Adding new LlvmType called LMStructP that represents an unpacked
  struct (this is necessary since LLVM's instructions the
  llvm.sadd.with.overflow.* return an unpacked struct).

- Modifications to LlvmCodeGen.CodeGen to generate the LLVM
  instructions for the primops.

- Modifications to StgCmmPrim to actually use those three instructions
  if we use the LLVM backend (so far they were only used for NCG).

Test Plan: validate

Reviewers: austin, rwbarton, bgamari

Reviewed By: bgamari

Subscribers: thomie, bgamari

Differential Revision: https://phabricator.haskell.org/D991

GHC Trac Issues: #9430

1 files changed, 8 insertions, 0 deletions

diff --git a/compiler/llvmGen/Llvm/AbsSyn.hs b/compiler/llvmGen/Llvm/AbsSyn.hs
index b0eae2cbfe..8a53df00fe 100644
--- a/compiler/llvmGen/Llvm/AbsSyn.hs
+++ b/compiler/llvmGen/Llvm/AbsSyn.hs
@@ -209,6 +209,14 @@ data LlvmExpression
   | Extract LlvmVar LlvmVar
 
   {- |
+    Extract a scalar element from a structure
+      * val: The structure
+      * idx: The index of the scalar within the structure
+    Corresponds to "extractvalue" instruction.
+  -}
+  | ExtractV LlvmVar Int
+
+  {- |
     Insert a scalar element into a vector
       * val:   The source vector
       * elt:   The scalar to insert