Merge pull request #85 from iovisor/bug

save bytes on comm usage

src/ast/semantic_analyser.cpp

@@ -48,7 +48,7 @@ void SemanticAnalyser::visit(Builtin &builtin)
     needs_stackid_map_ = true;
   }
   else if (builtin.ident == "comm") {
-    builtin.type = SizedType(Type::string, STRING_SIZE);
+    builtin.type = SizedType(Type::string, COMM_SIZE);
   }
   else if (builtin.ident == "func") {
     for (auto &attach_point : *probe_->attach_points)

src/types.h

@@ -10,6 +10,7 @@ namespace bpftrace {
 
 const int MAX_STACK_SIZE = 32;
 const int STRING_SIZE = 64;
+const int COMM_SIZE = 16;
 
 enum class Type
 {

tests/codegen.cpp

@@ -646,16 +646,16 @@ declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #1
 define i64 @"kprobe:f"(i8* nocapture readnone) local_unnamed_addr section "s_kprobe:f" {
 entry:
   %"@x_key" = alloca i64, align 8
-  %comm = alloca [64 x i8], align 1
-  %1 = getelementptr inbounds [64 x i8], [64 x i8]* %comm, i64 0, i64 0
+  %comm = alloca [16 x i8], align 1
+  %1 = getelementptr inbounds [16 x i8], [16 x i8]* %comm, i64 0, i64 0
   call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull %1)
-  call void @llvm.memset.p0i8.i64(i8* nonnull %1, i8 0, i64 64, i32 1, i1 false)
-  %get_comm = call i64 inttoptr (i64 16 to i64 (i8*, i64)*)([64 x i8]* nonnull %comm, i64 64)
+  call void @llvm.memset.p0i8.i64(i8* nonnull %1, i8 0, i64 16, i32 1, i1 false)
+  %get_comm = call i64 inttoptr (i64 16 to i64 (i8*, i64)*)([16 x i8]* nonnull %comm, i64 16)
   %2 = bitcast i64* %"@x_key" to i8*
   call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull %2)
   store i64 0, i64* %"@x_key", align 8
   %pseudo = call i64 @llvm.bpf.pseudo(i64 1, i64 1)
-  %update_elem = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo, i64* nonnull %"@x_key", [64 x i8]* nonnull %comm, i64 0)
+  %update_elem = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo, i64* nonnull %"@x_key", [16 x i8]* nonnull %comm, i64 0)
   call void @llvm.lifetime.end.p0i8(i64 -1, i8* nonnull %2)
   call void @llvm.lifetime.end.p0i8(i64 -1, i8* nonnull %1)
   ret i64 0
@@ -2075,22 +2075,22 @@ define i64 @"kprobe:f"(i8* nocapture readnone) local_unnamed_addr section "s_kpr
 entry:
   %"@y_key" = alloca i64, align 8
   %"@x_key" = alloca i64, align 8
-  %comm = alloca [64 x i8], align 1
-  %1 = getelementptr inbounds [64 x i8], [64 x i8]* %comm, i64 0, i64 0
+  %comm = alloca [16 x i8], align 1
+  %1 = getelementptr inbounds [16 x i8], [16 x i8]* %comm, i64 0, i64 0
   call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull %1)
-  call void @llvm.memset.p0i8.i64(i8* nonnull %1, i8 0, i64 64, i32 1, i1 false)
-  %get_comm = call i64 inttoptr (i64 16 to i64 (i8*, i64)*)([64 x i8]* nonnull %comm, i64 64)
+  call void @llvm.memset.p0i8.i64(i8* nonnull %1, i8 0, i64 16, i32 1, i1 false)
+  %get_comm = call i64 inttoptr (i64 16 to i64 (i8*, i64)*)([16 x i8]* nonnull %comm, i64 16)
   %2 = bitcast i64* %"@x_key" to i8*
   call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull %2)
   store i64 0, i64* %"@x_key", align 8
   %pseudo = call i64 @llvm.bpf.pseudo(i64 1, i64 1)
-  %update_elem = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo, i64* nonnull %"@x_key", [64 x i8]* nonnull %comm, i64 0)
+  %update_elem = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo, i64* nonnull %"@x_key", [16 x i8]* nonnull %comm, i64 0)
   call void @llvm.lifetime.end.p0i8(i64 -1, i8* nonnull %2)
   %3 = bitcast i64* %"@y_key" to i8*
   call void @llvm.lifetime.start.p0i8(i64 -1, i8* nonnull %3)
   store i64 0, i64* %"@y_key", align 8
   %pseudo1 = call i64 @llvm.bpf.pseudo(i64 1, i64 2)
-  %update_elem2 = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo1, i64* nonnull %"@y_key", [64 x i8]* nonnull %comm, i64 0)
+  %update_elem2 = call i64 inttoptr (i64 2 to i64 (i8*, i8*, i8*, i64)*)(i64 %pseudo1, i64* nonnull %"@y_key", [16 x i8]* nonnull %comm, i64 0)
   call void @llvm.lifetime.end.p0i8(i64 -1, i8* nonnull %3)
   ret i64 0
 }