AMDGPU/SI: Fix crash caused by r284267

[nhaehnle]

LGTM, just one small comment.

test/CodeGen/AMDGPU/mul_int24.ll

150–152 ↗

(On Diff #75183)

Add a GCN-LABEL.

llvm/trunk/lib/Target/AMDGPU/AMDGPUISelLowering.cpp

SDValue AMDGPUTargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::MULHS:
     return performMulhsCombine(N, DCI);
   case ISD::MULHU:
     return performMulhuCombine(N, DCI);
   case AMDGPUISD::MUL_I24:
   case AMDGPUISD::MUL_U24:
   case AMDGPUISD::MULHI_I24:
   case AMDGPUISD::MULHI_U24: {
-    simplifyI24(N, 0, DCI);
-    simplifyI24(N, 1, DCI);
+    // If the first call to simplify is successfull, then N may end up being
+    // deleted, so we shouldn't call simplifyI24 again.
+    simplifyI24(N, 0, DCI) || simplifyI24(N, 1, DCI);
     return SDValue();
   }
   case AMDGPUISD::MUL_LOHI_I24:
   case AMDGPUISD::MUL_LOHI_U24:
     return performMulLoHi24Combine(N, DCI);
   case ISD::SELECT:
     return performSelectCombine(N, DCI);
   case AMDGPUISD::BFE_I32:

llvm/trunk/test/CodeGen/AMDGPU/mul_int24.ll

entry:
   %b_24 = ashr i33 %tmp1, 9
   %tmp2 = mul i33 %a_24, %b_24
   %hi = lshr i33 %tmp2, 32
   %trunc = trunc i33 %hi to i32
 
   store i32 %trunc, i32 addrspace(1)* %out
   ret void
 }
+
+; GCN-LABEL: {{^}}simplify_i24_crash:
+; GCN: v_mul_i32_i24_e32 v[[VAL_LO:[0-9]+]]
+; GCN: v_mov_b32_e32 v[[VAL_HI:[0-9]+]], v[[VAL_LO]]
+; GCN: buffer_store_dwordx2 v{{\[}}[[VAL_LO]]:[[VAL_HI]]{{\]}}
+define void @simplify_i24_crash(<2 x i32> addrspace(1)* %out, i32 %arg0, <2 x i32> %arg1, <2 x i32> %arg2) {
+bb:
+  %cmp = icmp eq i32 %arg0, 0
+  br i1 %cmp, label %bb11, label %bb7
+
+bb11:
+  %tmp14 = shufflevector <2 x i32> %arg1, <2 x i32> undef, <2 x i32> zeroinitializer
+  %tmp16 = shufflevector <2 x i32> %arg2, <2 x i32> undef, <2 x i32> zeroinitializer
+  %tmp17 = shl <2 x i32> %tmp14, <i32 8, i32 8>
+  %tmp18 = ashr <2 x i32> %tmp17, <i32 8, i32 8>
+  %tmp19 = shl <2 x i32> %tmp16, <i32 8, i32 8>
+  %tmp20 = ashr <2 x i32> %tmp19, <i32 8, i32 8>
+  %tmp21 = mul <2 x i32> %tmp18, %tmp20
+  store <2 x i32> %tmp21, <2 x i32> addrspace(1)* %out
+  br label %bb7
+
+bb7:
+  ret void
+
+}
 attributes #0 = { nounwind }