[X86][AMX] Fix bug for amx cast tranform

After combining amx cast operation, some amx cast intrinsic may be dead
code. This patch is to delete such dead code and avoid crash.

diff --git a/llvm/lib/Target/X86/X86LowerAMXType.cpp b/llvm/lib/Target/X86/X86LowerAMXType.cpp
index 6206d8e..b85bd82 100644 (file)
--- a/llvm/lib/Target/X86/X86LowerAMXType.cpp
+++ b/llvm/lib/Target/X86/X86LowerAMXType.cpp
@@ -947,6 +947,10 @@ bool X86LowerAMXCast::transformAMXCast(IntrinsicInst *AMXCast) {
     //                                                  i64 60)
     // call void @llvm.x86.tilestored64.internal(i16 15, i16 60,
     //                                           i8* %addr3, i64 60, x86_amx %2)
+    if (AMXCast->use_empty()) {
+      AMXCast->eraseFromParent();
+      return true;
+    }
     Use &U = *(AMXCast->use_begin());
     unsigned OpNo = U.getOperandNo();
     auto *II = dyn_cast<IntrinsicInst>(U.getUser());

diff --git a/llvm/test/CodeGen/X86/AMX/lat-transform-amx-bitcast.ll b/llvm/test/CodeGen/X86/AMX/lat-transform-amx-bitcast.ll
index 98a8201..6080344 100644 (file)
--- a/llvm/test/CodeGen/X86/AMX/lat-transform-amx-bitcast.ll
+++ b/llvm/test/CodeGen/X86/AMX/lat-transform-amx-bitcast.ll
@@ -415,6 +415,46 @@ define dso_local void @__tile_stored(i8* %0, i64 %1, %struct.__tile_str* nocaptu
   ret void
 }
 
+define void @dead_code(i8 *%buf) {
+; CHECK-LABEL: @dead_code(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = alloca <256 x i32>, align 64
+; CHECK-NEXT:    br i1 undef, label [[L1:%.*]], label [[L2:%.*]]
+; CHECK:       l1:
+; CHECK-NEXT:    [[T1:%.*]] = call x86_amx @llvm.x86.tilezero.internal(i16 8, i16 32)
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast <256 x i32>* [[TMP0]] to i8*
+; CHECK-NEXT:    call void @llvm.x86.tilestored64.internal(i16 8, i16 32, i8* [[TMP1]], i64 32, x86_amx [[T1]])
+; CHECK-NEXT:    [[TMP2:%.*]] = load <256 x i32>, <256 x i32>* [[TMP0]], align 1024
+; CHECK-NEXT:    br i1 undef, label [[L2]], label [[EXIT:%.*]]
+; CHECK:       l2:
+; CHECK-NEXT:    [[T3:%.*]] = phi <256 x i32> [ undef, [[ENTRY:%.*]] ], [ [[TMP2]], [[L1]] ]
+; CHECK-NEXT:    [[P:%.*]] = bitcast i8* [[BUF:%.*]] to <256 x i32>*
+; CHECK-NEXT:    store <256 x i32> [[T3]], <256 x i32>* [[P]], align 1024
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 undef, label %l1, label %l2
+
+l1:
+  %t1 = call x86_amx @llvm.x86.tilezero.internal(i16 8, i16 32)
+  %t2 = call <256 x i32> @llvm.x86.cast.tile.to.vector.v256i32(x86_amx %t1)
+  br i1 undef, label %l2, label %exit
+
+l2:
+  %t3 = phi <256 x i32> [ undef, %entry ], [ %t2, %l1 ]
+  %t4 = call x86_amx @llvm.x86.cast.vector.to.tile.v256i32(<256 x i32> %t3)
+  %t5 = call <256 x i32> @llvm.x86.cast.tile.to.vector.v256i32(x86_amx %t4)
+  %p = bitcast i8* %buf to <256 x i32>*
+  store <256 x i32> %t5, <256 x i32>* %p
+  br label %exit
+
+exit:
+  ret void
+}
+
+declare x86_amx @llvm.x86.tilezero.internal(i16, i16)
 declare x86_amx @llvm.x86.tileloadd64.internal(i16, i16, i8*, i64)
 declare x86_amx @llvm.x86.tdpbssd.internal(i16, i16, i16, x86_amx, x86_amx, x86_amx)
 declare x86_amx @llvm.x86.tdpbsud.internal(i16, i16, i16, x86_amx, x86_amx, x86_amx)