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[DWARF] Preserve column number when emitting 'line 0' record 

Follow-up to r289256, address a FIXME to avoid resetting the column
number. This reduced .debug_line by 2.6% in a RelWithDebInfo
self-build of clang.

llvm-svn: 289620
This commit is contained in:
Paul Robinson 2016-12-14 00:27:35 +00:00
parent f6b069c7db
commit 8fec3da00c
4 changed files with 14 additions and 10 deletions
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13
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
View File

@ -1048,11 +1048,16 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
// location from the physically previous (maybe unrelated) block.
if (UnknownLocations == Enable || PrevLabel ||
(PrevInstBB && PrevInstBB != MI->getParent())) {
// Preserve the file number, if we can, to save space in the line table.
// Preserve the file and column numbers, if we can, to save space in
// the encoded line table.
// Do not update PrevInstLoc, it remembers the last non-0 line.
// FIXME: Also preserve the column number, to save more space?
const MDNode *Scope = PrevInstLoc ? PrevInstLoc.getScope() : nullptr;
recordSourceLine(0, 0, Scope, 0);
const MDNode *Scope = nullptr;
unsigned Column = 0;
if (PrevInstLoc) {
Scope = PrevInstLoc.getScope();
Column = PrevInstLoc.getCol();
}
recordSourceLine(/*Line=*/0, Column, Scope, /*Flags=*/0);
}
return;
}

5
llvm/test/CodeGen/X86/unknown-location.ll
View File

@ -1,11 +1,10 @@
; RUN: llc < %s -asm-verbose=false -mtriple=x86_64-apple-darwin10 -use-unknown-locations=Enable | FileCheck %s
; The divide instruction does not have a debug location. CodeGen should
; represent this in the debug information. This is done by setting line
; and column to 0
; represent this in the debug information. This is done by setting line to 0.
; CHECK: leal
; CHECK-NEXT: .loc 1 0 0
; CHECK-NEXT: .loc 1 0 3
; CHECK: cltd
; CHECK-NEXT: idivl
; CHECK-NEXT: .loc 1 4 3

4
llvm/test/DebugInfo/X86/dwarf-no-source-loc.ll
View File

@ -42,11 +42,11 @@ if.end: ; preds = %if.then, %entry
; CHECK: .loc 1 7 7
; CHECK-NOT: .loc
; CHECK: .loc 1 0 0 is_stmt 0
; CHECK: .loc 1 0 7 is_stmt 0
; CHECK-NOT: .loc
; CHECK: .loc 2 20 5 is_stmt 1
; CHECK: .LBB0_2:
; CHECK-NEXT: .loc 2 0 0 is_stmt 0
; CHECK-NEXT: .loc 2 0 5 is_stmt 0
; CHECK-NOT: .loc
; CHECK: .loc 1 10 3 is_stmt 1
;

2
llvm/test/DebugInfo/X86/tail-merge.ll
View File

@ -27,7 +27,7 @@
; CHECK: .loc 1 8 10
; CHECK: callq bar
; CHECK: [[TAIL]]:
; CHECK: .loc 1 0 0
; CHECK: .loc 1 0
; CHECK: addl [[REG]], %eax
; CHECK: .loc 1 9 3