[PATCH] D93740: [X86] Canonicalize AMX bitcast instruction.

[LuoYuanke via Phabricator via llvm-commits]

LuoYuanke updated this revision to Diff 313473.
LuoYuanke added a comment.

Move comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93740/new/

https://reviews.llvm.org/D93740

Files:
  llvm/lib/Target/X86/X86LowerAMXType.cpp
  llvm/test/CodeGen/X86/AMX/amx-type.ll


Index: llvm/test/CodeGen/X86/AMX/amx-type.ll
===================================================================
--- llvm/test/CodeGen/X86/AMX/amx-type.ll
+++ llvm/test/CodeGen/X86/AMX/amx-type.ll
@@ -8,6 +8,17 @@
 @buf = dso_local global [1024 x i8] zeroinitializer, align 16
 @buf2 = dso_local global [1024 x i8] zeroinitializer, align 16
 
+define dso_local <256 x i32> @test_amx_bitcast(<256 x i32> %in) #2 {
+; CHECK-LABEL: @test_amx_bitcast(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret <256 x i32> [[IN:%.*]]
+;
+entry:
+  %amx = bitcast <256 x i32> %in to x86_amx
+  %vec = bitcast x86_amx %amx to <256 x i32>
+  ret <256 x i32> %vec
+}
+
 define dso_local void @test_amx_store(<256 x i32>* %in, i16 %m, i16 %n, i8 *%buf, i64 %s) #2 {
 ; CHECK-LABEL: @test_amx_store(
 ; CHECK-NEXT:  entry:
Index: llvm/lib/Target/X86/X86LowerAMXType.cpp
===================================================================
--- llvm/lib/Target/X86/X86LowerAMXType.cpp
+++ llvm/lib/Target/X86/X86LowerAMXType.cpp
@@ -261,6 +261,7 @@
 
 bool X86LowerAMXType::visit() {
   SmallVector<Instruction *, 8> DeadInsts;
+  SmallVector<Instruction *, 2> DeadBitcasts;
 
   for (BasicBlock *BB : post_order(&Func)) {
     for (BasicBlock::reverse_iterator II = BB->rbegin(), IE = BB->rend();
@@ -272,6 +273,23 @@
 
       Value *Src = Bitcast->getOperand(0);
       Type *Ty = Bitcast->getType();
+      auto CanonicalizeBitcast = [&]() {
+        if (Bitcast->user_empty()) {
+          DeadBitcasts.push_back(Bitcast);
+          return true;
+        }
+        bool Change = false;
+        Value *DstV = Src, *PreDst = Bitcast, *SrcV;
+        while (match(DstV, m_BitCast(m_Value(SrcV))) &&
+               SrcV->getType()->getTypeID() == PreDst->getType()->getTypeID()) {
+          PreDst->replaceAllUsesWith(SrcV);
+          DeadBitcasts.push_back(cast<Instruction>(PreDst));
+          PreDst = DstV;
+          DstV = SrcV;
+          Change = true;
+        }
+        return Change;
+      };
 
       if (Ty->isPointerTy() &&
           cast<PointerType>(Ty)->getElementType()->isX86_AMXTy()) {
@@ -302,10 +320,8 @@
         // store <256 x i32> %2, <256 x i32>* %0, align 64
       }
       if (Bitcast->getType()->isX86_AMXTy()) {
-        if (Bitcast->user_empty()) {
-          DeadInsts.push_back(Bitcast);
+        if (CanonicalizeBitcast())
           continue;
-        }
         LoadInst *LD = dyn_cast<LoadInst>(Src);
         if (!LD) {
           if (transformBitcast(Bitcast))
@@ -333,10 +349,8 @@
         if (LD->hasOneUse())
           DeadInsts.push_back(LD);
       } else if (Src->getType()->isX86_AMXTy()) {
-        if (Bitcast->user_empty()) {
-          DeadInsts.push_back(Bitcast);
+        if (CanonicalizeBitcast())
           continue;
-        }
         StoreInst *ST = nullptr;
         for (auto UI = Bitcast->use_begin(), UE = Bitcast->use_end();
              UI != UE;) {
@@ -378,7 +392,7 @@
     }
   }
 
-  bool C = !DeadInsts.empty();
+  bool C = !DeadInsts.empty() || !DeadBitcasts.empty();
 
   SmallSet<Instruction *, 8> DeletedInst;
   auto DeleteInst = [&](Instruction *Inst) {
@@ -401,6 +415,8 @@
   };
   for (auto *Inst : DeadInsts)
     DeleteInst(Inst);
+  for (auto *Inst : DeadBitcasts)
+    DeleteInst(Inst);
 
   return C;
 }


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