Add a pass to lower is.constant and objectsize intrinsics

This pass lowers is.constant and objectsize intrinsics not simplified by
earlier constant folding, i.e. if the object given is not constant or if
not using the optimized pass chain. The result is recursively simplified
and constant conditionals are pruned, so that dead blocks are removed
even for -O0. This allows inline asm blocks with operand constraints to
work all the time.

The new pass replaces the existing lowering in the codegen-prepare pass
and fallbacks in SDAG/GlobalISEL and FastISel. The latter now assert
on the intrinsics.

Differential Revision: https://reviews.llvm.org/D65280

llvm-svn: 374743

1 files changed, 4 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 0594d5f..061c8e5 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -1868,24 +1868,10 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
       });
       return true;
     }
-    case Intrinsic::objectsize: {
-      // Lower all uses of llvm.objectsize.*
-      Value *RetVal =
-          lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
-
-      resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
-        replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
-      });
-      return true;
-    }
-    case Intrinsic::is_constant: {
-      // If is_constant hasn't folded away yet, lower it to false now.
-      Constant *RetVal = ConstantInt::get(II->getType(), 0);
-      resetIteratorIfInvalidatedWhileCalling(BB, [&]() {
-        replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
-      });
-      return true;
-    }
+    case Intrinsic::objectsize:
+      llvm_unreachable("llvm.objectsize.* should have been lowered already");
+    case Intrinsic::is_constant:
+      llvm_unreachable("llvm.is.constant.* should have been lowered already");
     case Intrinsic::aarch64_stlxr:
     case Intrinsic::aarch64_stxr: {
       ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));