[GlobalISel] Support ConstantAsMetadata in IRTranslator

[zuban32]

Summary

When using instructions which have a MetadataAsValue argument
(e.g. some target-specific intrinsics)
MD canonicalization strips internal MDNodes with a
single ConstantAsMetadata child. That prevented IRTranslator
from the proper translation of such a calls.

[paquette]

Can you add a testcase?

[zuban32]

In D108375#2955777, @paquette wrote:

Can you add a testcase?

That's the problem, I couldn't find an in-tree target matching the usecase i.e. having some instruction (likely an intrinsic) accepting metadata argument

[zuban32]

Fix clang-tidy warning

[zuban32]

Gentle ping

[paquette]

LGTM

[zuban32]

Can someone pls commit this? I don't have an access to do that myself

[zuban32]

In D108375#2967518, @zuban32 wrote:

Can someone pls commit this? I don't have an access to do that myself

Ping

[arsenm]

In D108375#2957136, @zuban32 wrote:

In D108375#2955777, @paquette wrote:

Can you add a testcase?

That's the problem, I couldn't find an in-tree target matching the usecase i.e. having some instruction (likely an intrinsic) accepting metadata argument

llvm.amdgcn.reloc.constant uses a metadata argument

[zuban32]

Rebased, added a test.

[zuban32]

Someone pls commit this, I don't have an access

[zuban32]

Ping

[arsenm]

624e4d087efdb2f26a9a618dd0e2da99782e6308

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

if (CI.paramHasAttr(Arg.index(), Attribute::ImmArg)) {
         // imm arguments are more convenient than cimm (and realistically
         // probably sufficient), so use them.
         assert(CI->getBitWidth() <= 64 &&
                "large intrinsic immediates not handled");
         MIB.addImm(CI->getSExtValue());
       } else {
         MIB.addFPImm(cast<ConstantFP>(Arg.value()));
       }
-    } else if (auto MD = dyn_cast<MetadataAsValue>(Arg.value())) {
-      auto *MDN = dyn_cast<MDNode>(MD->getMetadata());
-      if (!MDN) // This was probably an MDString.
+    } else if (auto *MDVal = dyn_cast<MetadataAsValue>(Arg.value())) {
+      auto *MD = MDVal->getMetadata();
+      auto *MDN = dyn_cast<MDNode>(MD);
+      if (!MDN) {
+        if (auto *ConstMD = dyn_cast<ConstantAsMetadata>(MD))
+          MDN = MDNode::get(MF->getFunction().getContext(), ConstMD);
+        else // This was probably an MDString.
           return false;
+      }
       MIB.addMetadata(MDN);
     } else {
       ArrayRef<Register> VRegs = getOrCreateVRegs(*Arg.value());
       if (VRegs.size() > 1)
         return false;
       MIB.addUse(VRegs[0]);
     }
   }

llvm/test/CodeGen/AMDGPU/GlobalISel/irtranslator-metadata.ll

 ; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 ; RUN: llc -global-isel -march=amdgcn -mcpu=gfx900 -stop-after=irtranslator -o - %s | FileCheck %s
 ; Make sure intrinsics with metadata arguments are translated
 
 define i32 @reloc_constant() {
   ; CHECK-LABEL: name: reloc_constant
   ; CHECK: bb.1 (%ir-block.0):
   ; CHECK:   liveins: $sgpr30_sgpr31
   ; CHECK:   [[COPY:%[0-9]+]]:sgpr_64 = COPY $sgpr30_sgpr31
-  ; CHECK:   [[INT:%[0-9]+]]:_(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.reloc.constant), !0
-  ; CHECK:   $vgpr0 = COPY [[INT]](s32)
+  ; CHECK:   [[INT0:%[0-9]+]]:_(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.reloc.constant), !0
+  ; We cannot have any specific metadata check here as ConstantAsMetadata is printed as <raw_ptr_val>
+  ; CHECK:   [[INT1:%[0-9]+]]:_(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.reloc.constant), <0x{{[0-9a-f]+}}>
+  ; CHECK:   [[SUM:%[0-9]+]]:_(s32) = G_ADD [[INT0]], [[INT1]]
+  ; CHECK:   $vgpr0 = COPY [[SUM]](s32)
   ; CHECK:   [[COPY1:%[0-9]+]]:ccr_sgpr_64 = COPY [[COPY]]
   ; CHECK:   S_SETPC_B64_return [[COPY1]], implicit $vgpr0
-  %val = call i32 @llvm.amdgcn.reloc.constant(metadata !0)
-  ret i32 %val
+  %val0 = call i32 @llvm.amdgcn.reloc.constant(metadata !0)
+  %val1 = call i32 @llvm.amdgcn.reloc.constant(metadata i32 4)
+  %res = add i32 %val0, %val1
+  ret i32 %res
 }
 
 declare i32 @llvm.amdgcn.reloc.constant(metadata) #0
 
 attributes #0 = { nounwind readnone speculatable willreturn }
 
 !0 = !{!"arst"}