From 84188296e93dd4d26cb0a75a03a9096794e01e2f Mon Sep 17 00:00:00 2001 From: Alessandro Arzilli Date: Tue, 4 Jul 2017 09:11:04 +0200 Subject: [PATCH] cmd/compile: more compact representation of DW_AT_high_pc DWARF version 4 allows DW_AT_high_pc to be represented as a constant offset from DW_AT_low_pc, this can help save up to 7 bytes per function/lexical scope. Change-Id: I93638d83638ecad4d0d1bfe27348eae6139820c9 Reviewed-on: https://go-review.googlesource.com/60530 Run-TryBot: Heschi Kreinick Reviewed-by: Heschi Kreinick --- src/cmd/internal/dwarf/dwarf.go | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/src/cmd/internal/dwarf/dwarf.go b/src/cmd/internal/dwarf/dwarf.go index 3f12811338c..4beb8c4c61c 100644 --- a/src/cmd/internal/dwarf/dwarf.go +++ b/src/cmd/internal/dwarf/dwarf.go @@ -292,7 +292,7 @@ var abbrevs = [DW_NABRV]dwAbbrev{ []dwAttrForm{ {DW_AT_name, DW_FORM_string}, {DW_AT_low_pc, DW_FORM_addr}, - {DW_AT_high_pc, DW_FORM_addr}, + {DW_AT_high_pc, DW_FORM_udata}, {DW_AT_frame_base, DW_FORM_block1}, {DW_AT_external, DW_FORM_flag}, }, @@ -373,7 +373,7 @@ var abbrevs = [DW_NABRV]dwAbbrev{ DW_CHILDREN_yes, []dwAttrForm{ {DW_AT_low_pc, DW_FORM_addr}, - {DW_AT_high_pc, DW_FORM_addr}, + {DW_AT_high_pc, DW_FORM_udata}, }, }, @@ -740,7 +740,7 @@ func PutFunc(ctxt Context, info, loc, ranges Sym, name string, external bool, st Uleb128put(ctxt, info, DW_ABRV_FUNCTION) putattr(ctxt, info, DW_ABRV_FUNCTION, DW_FORM_string, DW_CLS_STRING, int64(len(name)), name) putattr(ctxt, info, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, 0, startPC) - putattr(ctxt, info, DW_ABRV_FUNCTION, DW_FORM_addr, DW_CLS_ADDRESS, size, startPC) + putattr(ctxt, info, DW_ABRV_FUNCTION, DW_FORM_udata, DW_CLS_CONSTANT, size, nil) putattr(ctxt, info, DW_ABRV_FUNCTION, DW_FORM_block1, DW_CLS_BLOCK, 1, []byte{DW_OP_call_frame_cfa}) var ev int64 if external { @@ -772,7 +772,7 @@ func putscope(ctxt Context, info, loc, ranges, startPC Sym, curscope int32, scop if len(scope.Ranges) == 1 { Uleb128put(ctxt, info, DW_ABRV_LEXICAL_BLOCK_SIMPLE) putattr(ctxt, info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].Start, startPC) - putattr(ctxt, info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_addr, DW_CLS_ADDRESS, scope.Ranges[0].End, startPC) + putattr(ctxt, info, DW_ABRV_LEXICAL_BLOCK_SIMPLE, DW_FORM_udata, DW_CLS_CONSTANT, scope.Ranges[0].End-scope.Ranges[0].Start, nil) } else { Uleb128put(ctxt, info, DW_ABRV_LEXICAL_BLOCK_RANGES) putattr(ctxt, info, DW_ABRV_LEXICAL_BLOCK_RANGES, DW_FORM_sec_offset, DW_CLS_PTR, ranges.Len(), ranges)