[SYCL][ESIMD] Fix crashes of sycl-post-link (#7673)

This is to have sycl-post-link to handle IR in the form

```
%0 = load i64, i64 addrspace(1)* getelementptr (<3 x i64>, <3 x i64> addrspace(1)* @__spirv_BuiltInGlobalInvocationId, i64 0, i64 0), align 32
  store i64 %0, i64 addrspace(1)* %_arg_DoNotOptimize, align 8
```

Author: fineg74

llvm/lib/SYCLLowerIR/ESIMD/LowerESIMD.cpp

@@ -44,6 +44,7 @@ using namespace llvm;
 namespace id = itanium_demangle;
 using namespace llvm::esimd;
 
+#undef DEBUG_TYPE
 #define DEBUG_TYPE "lower-esimd"
 
 #define SLM_BTI 254
@@ -1130,8 +1131,11 @@ static Instruction *generateGenXCall(Instruction *EEI, StringRef IntrinName,
           ? GenXIntrinsic::getGenXDeclaration(
                 EEI->getModule(), ID, FixedVectorType::get(I32Ty, MAX_DIMS))
           : GenXIntrinsic::getGenXDeclaration(EEI->getModule(), ID);
-
-  std::string ResultName = (Twine(EEI->getName()) + "." + FullIntrinName).str();
+  // Use hardcoded prefix when EEI has no name.
+  std::string ResultName =
+      ((EEI->hasName() ? Twine(EEI->getName()) : Twine("Res")) + "." +
+       FullIntrinName)
+          .str();
   Instruction *Inst = IntrinsicInst::Create(NewFDecl, {}, ResultName, EEI);
   Inst->setDebugLoc(EEI->getDebugLoc());
 
@@ -1181,6 +1185,48 @@ bool translateLLVMIntrinsic(CallInst *CI) {
   return true; // "intrinsic has been translated, erase the original call"
 }
 
+// Generate translation instructions for SPIRV global function calls
+static Value *generateSpirvGlobalGenX(Instruction *EEI,
+                                      StringRef SpirvGlobalName,
+                                      uint64_t IndexValue) {
+  Value *NewInst = nullptr;
+  if (SpirvGlobalName == "WorkgroupSize") {
+    NewInst = generateGenXCall(EEI, "local.size", true, IndexValue);
+  } else if (SpirvGlobalName == "LocalInvocationId") {
+    NewInst = generateGenXCall(EEI, "local.id", true, IndexValue);
+  } else if (SpirvGlobalName == "WorkgroupId") {
+    NewInst = generateGenXCall(EEI, "group.id", false, IndexValue);
+  } else if (SpirvGlobalName == "GlobalInvocationId") {
+    // GlobalId = LocalId + WorkGroupSize * GroupId
+    Instruction *LocalIdI = generateGenXCall(EEI, "local.id", true, IndexValue);
+    Instruction *WGSizeI =
+        generateGenXCall(EEI, "local.size", true, IndexValue);
+    Instruction *GroupIdI =
+        generateGenXCall(EEI, "group.id", false, IndexValue);
+    Instruction *MulI =
+        BinaryOperator::CreateMul(WGSizeI, GroupIdI, "mul", EEI);
+    NewInst = BinaryOperator::CreateAdd(LocalIdI, MulI, "add", EEI);
+  } else if (SpirvGlobalName == "GlobalSize") {
+    // GlobalSize = WorkGroupSize * NumWorkGroups
+    Instruction *WGSizeI =
+        generateGenXCall(EEI, "local.size", true, IndexValue);
+    Instruction *NumWGI =
+        generateGenXCall(EEI, "group.count", true, IndexValue);
+    NewInst = BinaryOperator::CreateMul(WGSizeI, NumWGI, "mul", EEI);
+  } else if (SpirvGlobalName == "GlobalOffset") {
+    // TODO: Support GlobalOffset SPIRV intrinsics
+    // Currently all users of load of GlobalOffset are replaced with 0.
+    NewInst = llvm::Constant::getNullValue(EEI->getType());
+  } else if (SpirvGlobalName == "NumWorkgroups") {
+    NewInst = generateGenXCall(EEI, "group.count", true, IndexValue);
+  }
+
+  llvm::esimd::assert_and_diag(
+      NewInst, "Load from global SPIRV builtin was not translated");
+
+  return NewInst;
+}
+
 /// Replaces the load \p LI of SPIRV global with corresponding call(s) of GenX
 /// intrinsic(s). The users of \p LI may also be transformed if needed for
 /// def/use type correctness.
@@ -1207,6 +1253,12 @@ translateSpirvGlobalUses(LoadInst *LI, StringRef SpirvGlobalName,
                                               llvm::APInt(32, 1, true));
   } else if (SpirvGlobalName == "GlobalLinearId") {
     NewInst = llvm::Constant::getNullValue(LI->getType());
+  } else if (isa<GetElementPtrConstantExpr>(LI->getPointerOperand())) {
+    // Translate the load that has getelementptr as an operand
+    auto *GEPCE = cast<GetElementPtrConstantExpr>(LI->getPointerOperand());
+    uint64_t IndexValue =
+        cast<Constant>(GEPCE->getOperand(2))->getUniqueInteger().getZExtValue();
+    NewInst = generateSpirvGlobalGenX(LI, SpirvGlobalName, IndexValue);
   }
   if (NewInst) {
     LI->replaceAllUsesWith(NewInst);
@@ -1215,62 +1267,16 @@ translateSpirvGlobalUses(LoadInst *LI, StringRef SpirvGlobalName,
   }
 
   // Only loads from _vector_ SPIRV globals reach here now. Their users are
-  // expected to be ExtractElementInst or TruncInst only, and they are replaced
-  // in this loop. When loads from _scalar_ SPIRV globals are handled here as
-  // well, the users will not be replaced by new instructions, but the GenX call
-  // replacing the original load 'LI' should be inserted before each user.
+  // expected to be ExtractElementInst only, and they are
+  // replaced in this loop. When loads from _scalar_ SPIRV globals are handled
+  // here as well, the users will not be replaced by new instructions, but the
+  // GenX call replacing the original load 'LI' should be inserted before each
+  // user.
   for (User *LU : LI->users()) {
-    assert(
-        (isa<ExtractElementInst>(LU) || isa<TruncInst>(LU)) &&
-        "SPIRV global users should be either ExtractElementInst or TruncInst");
-    Instruction *EEI = cast<Instruction>(LU);
-    NewInst = nullptr;
-
-    uint64_t IndexValue = 0;
-    if (isa<ExtractElementInst>(EEI)) {
-      IndexValue = getIndexFromExtract(cast<ExtractElementInst>(EEI));
-    } else {
-      auto *GEPCE = cast<GetElementPtrConstantExpr>(LI->getPointerOperand());
-
-      IndexValue = cast<Constant>(GEPCE->getOperand(2))
-                       ->getUniqueInteger()
-                       .getZExtValue();
-    }
-
-    if (SpirvGlobalName == "WorkgroupSize") {
-      NewInst = generateGenXCall(EEI, "local.size", true, IndexValue);
-    } else if (SpirvGlobalName == "LocalInvocationId") {
-      NewInst = generateGenXCall(EEI, "local.id", true, IndexValue);
-    } else if (SpirvGlobalName == "WorkgroupId") {
-      NewInst = generateGenXCall(EEI, "group.id", false, IndexValue);
-    } else if (SpirvGlobalName == "GlobalInvocationId") {
-      // GlobalId = LocalId + WorkGroupSize * GroupId
-      Instruction *LocalIdI =
-          generateGenXCall(EEI, "local.id", true, IndexValue);
-      Instruction *WGSizeI =
-          generateGenXCall(EEI, "local.size", true, IndexValue);
-      Instruction *GroupIdI =
-          generateGenXCall(EEI, "group.id", false, IndexValue);
-      Instruction *MulI =
-          BinaryOperator::CreateMul(WGSizeI, GroupIdI, "mul", EEI);
-      NewInst = BinaryOperator::CreateAdd(LocalIdI, MulI, "add", EEI);
-    } else if (SpirvGlobalName == "GlobalSize") {
-      // GlobalSize = WorkGroupSize * NumWorkGroups
-      Instruction *WGSizeI =
-          generateGenXCall(EEI, "local.size", true, IndexValue);
-      Instruction *NumWGI =
-          generateGenXCall(EEI, "group.count", true, IndexValue);
-      NewInst = BinaryOperator::CreateMul(WGSizeI, NumWGI, "mul", EEI);
-    } else if (SpirvGlobalName == "GlobalOffset") {
-      // TODO: Support GlobalOffset SPIRV intrinsics
-      // Currently all users of load of GlobalOffset are replaced with 0.
-      NewInst = llvm::Constant::getNullValue(EEI->getType());
-    } else if (SpirvGlobalName == "NumWorkgroups") {
-      NewInst = generateGenXCall(EEI, "group.count", true, IndexValue);
-    }
+    ExtractElementInst *EEI = cast<ExtractElementInst>(LU);
+    uint64_t IndexValue = getIndexFromExtract(cast<ExtractElementInst>(EEI));
 
-    llvm::esimd::assert_and_diag(
-        NewInst, "Load from global SPIRV builtin was not translated");
+    NewInst = generateSpirvGlobalGenX(EEI, SpirvGlobalName, IndexValue);
     EEI->replaceAllUsesWith(NewInst);
     InstsToErase.push_back(EEI);
   }