[OpenMP][OMPIRBuilder][MLIR] Rebase and replace old constant -> instruction transformation code with newer variation from recently landed PR

Author: agozillon

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

@@ -2110,11 +2110,6 @@ class OpenMPIRBuilder {
                                   int32_t UB);
   ///}
 
-  /// Replaces constant values with instruction equivelants where possible
-  /// inside of a function.
-  static void replaceConstantValueUsesInFuncWithInstr(llvm::Value *Input,
-                                                      Function *Func);
-
 private:
   // Sets the function attributes expected for the outlined function
   void setOutlinedTargetRegionFunctionAttributes(Function *OutlinedFn);

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -30,6 +30,7 @@
 #include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/ReplaceConstant.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
@@ -2913,10 +2914,14 @@ handleDeclareTargetMapVar(MapInfoData &mapData,
     // reference pointer and the pointer are assigned in the kernel argument
     // structure for the host.
     if (mapData.IsDeclareTarget[i]) {
-
-      moduleTranslation.getOpenMPBuilder()
-          ->replaceConstantValueUsesInFuncWithInstr(mapData.OriginalValue[i],
-                                                    func);
+      // If the original map value is a constant, then we have to make sure all
+      // of it's uses within the current kernel/function that we are going to
+      // rewrite are converted to instructions, as we will be altering the old
+      // use (OriginalValue) from a constant to an instruction, which will be
+      // illegal and ICE the compiler if the user is a constant expression of
+      // some kind e.g. a constant GEP.
+      if (auto *constant = dyn_cast<llvm::Constant>(mapData.OriginalValue[i]))
+        convertUsersOfConstantsToInstructions(constant, func, false);
 
       // The users iterator will get invalidated if we modify an element,
       // so we populate this vector of uses to alter each user on an