use default intrinsic attrs for BPF packet loads

The BPF packet load intrinsics lost attribute WillReturn due to 0b20c30. The attribute loss causes excessive bitshifting, resulting in previously working programs failing the BPF verifier due to instruction/complexity limits.

cherry picked only the BPF changes from 99a10f1

Signed-off-by: Bryce Kahle <[email protected]>

Author: brycekahle

llvm/include/llvm/IR/IntrinsicsBPF.td

@@ -13,11 +13,11 @@
 // Specialized loads from packet
 let TargetPrefix = "bpf" in {  // All intrinsics start with "llvm.bpf."
   def int_bpf_load_byte : ClangBuiltin<"__builtin_bpf_load_byte">,
-              Intrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
+              DefaultAttrsIntrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
   def int_bpf_load_half : ClangBuiltin<"__builtin_bpf_load_half">,
-              Intrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
+              DefaultAttrsIntrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
   def int_bpf_load_word : ClangBuiltin<"__builtin_bpf_load_word">,
-              Intrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
+              DefaultAttrsIntrinsic<[llvm_i64_ty], [llvm_ptr_ty, llvm_i64_ty], [IntrReadMem]>;
   def int_bpf_pseudo : ClangBuiltin<"__builtin_bpf_pseudo">,
               Intrinsic<[llvm_i64_ty], [llvm_i64_ty, llvm_i64_ty]>;
   def int_bpf_preserve_field_info : ClangBuiltin<"__builtin_bpf_preserve_field_info">,

llvm/test/CodeGen/BPF/sockex2.ll

@@ -311,7 +311,7 @@ flow_dissector.exit.thread:                       ; preds = %86, %12, %196, %199
 ; CHECK-LABEL: bpf_prog2:
 ; CHECK: r0 = *(u16 *)skb[12] # encoding: [0x28,0x00,0x00,0x00,0x0c,0x00,0x00,0x00]
 ; CHECK: r0 = *(u16 *)skb[16] # encoding: [0x28,0x00,0x00,0x00,0x10,0x00,0x00,0x00]
-; CHECK: implicit-def: $r8
+; CHECK: implicit-def: $r7
 ; CHECK: r1 =
 ; CHECK: call 1 # encoding: [0x85,0x00,0x00,0x00,0x01,0x00,0x00,0x00]
 ; CHECK: call 2 # encoding: [0x85,0x00,0x00,0x00,0x02,0x00,0x00,0x00]

llvm/test/Transforms/DCE/intrinsics-bpf.ll

@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S < %s -passes=dce  | FileCheck %s
+
+declare i64 @llvm.bpf.load.half(ptr, i64)
+declare i64 @llvm.bpf.load.word(ptr, i64)
+declare i64 @llvm.bpf.load.byte(ptr, i64)
+
+define void @test_bpf_load_half(ptr %a, i64 %b) {
+; CHECK-LABEL: define void @test_bpf_load_half(
+; CHECK-SAME: ptr [[A:%.*]], i64 [[B:%.*]]) {
+; CHECK-NEXT:    ret void
+;
+  %v = call i64 @llvm.bpf.load.half(ptr %a, i64 %b)
+  ret void
+}
+
+define void @test_bpf_load_word(ptr %a, i64 %b) {
+; CHECK-LABEL: define void @test_bpf_load_word(
+; CHECK-SAME: ptr [[A:%.*]], i64 [[B:%.*]]) {
+; CHECK-NEXT:    ret void
+;
+  %v = call i64 @llvm.bpf.load.word(ptr %a, i64 %b)
+  ret void
+}
+
+define void @test_bpf_load_byte(ptr %a, i64 %b) {
+; CHECK-LABEL: define void @test_bpf_load_byte(
+; CHECK-SAME: ptr [[A:%.*]], i64 [[B:%.*]]) {
+; CHECK-NEXT:    ret void
+;
+  %v = call i64 @llvm.bpf.load.byte(ptr %a, i64 %b)
+  ret void
+}