From fce2219764f00e1b6de75bca08d9b10a212165b5 Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl@apple.com>
Date: Mon, 5 Oct 2015 23:11:20 +0000
Subject: [PATCH] dsymutil: Don't prune forward declarations inside of an
 imported TAG_module if there exists not definition for the type. For this to
 work, we need to clone the imported modules before building the decl context
 chains of the DIEs in the non-skeleton CUs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249362 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/tools/dsymutil/Inputs/submodules/1.o     | Bin 2208 -> 2232 bytes
 .../dsymutil/Inputs/submodules/Parent.pcm     | Bin 25104 -> 25260 bytes
 test/tools/dsymutil/X86/submodules.m          |  16 +++++++++++++++-
 tools/dsymutil/DwarfLinker.cpp                |  17 +++++++++++------
 4 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/test/tools/dsymutil/Inputs/submodules/1.o b/test/tools/dsymutil/Inputs/submodules/1.o
index f95b70cd05cd20746926f53cecef077746164d19..d38e30f67c2c4f8031669ae48cdde5743400ef9b 100644
GIT binary patch
delta 519
zcmZ1=xI=J)gJ3T+0~mZ@fzZ7Z1Mf4|Og3b67n}hRfs-ARI~ncaqWw_uj>$I}?IqP2
zA>3O~QE@g1qhYckler)x6I2*VeVkm$WDgg$fs395irPZesz60`CrdKh3nrq822Rcd
zinc;U)1YcgC+}pom;3+~HGqmfU}s<e`EtT!K^AjK1*nH}p|S!T5XOwji7fh@3xGV3
zS2j$Z$udF0(%9HcQ$Zsqrz}^$q^LA6TfxZ0(%8sovLmZBt7~pSN#*2d)@_VyCJV8-
zq%sEp^?3lXJ;*>7Mm-BKrSA%)SV2M{AOggU;VD3p$zVE=WMi6G0dfhPS5O4z%>$AQ
z?3qA<m4#z5km6VY5-6X%oK1z(anY?CKpsQb<ST6YoFKzMPEMT6!``m|(gNav42K3`
bIaCN_g39E*?2U~2lkGV)8IvYwa+m`ETZc?=

delta 506
zcmdlXxIl1%gJ3B$0~mZ@fzYKB1Mf4IO*Uk77n}qUfs;*>I~ncaqWw_urpY%M?Ijf%
zA>3n7Q9(8cBV)25leyq?s4P^H;rirCCVRN34OIC0<dZ;AWhMw$1u7~$S(4da&>c<G
zd~zmGG#e_K22~q9c_*{I<PE5(0aWw^I|BpAmlcx*S<EFlpdQYJ%KiY#f<VLML>7I{
z4h{wekYi^|p2;#n!otMTOjAK4C#Nh|zoe)%FI&OL1Sn=c*^yOxauVxS#u<|(*jxe`
zSQynTfSOoA=74|*5Hp6y0ZAtHW+2JNG_fKbnOBel=5+x{2KHni!OFq`3Q&$IAc4Zk
z2ia6OYbLIJ3gj^aOn%3vF90$O<S<{55D-ibWY?J-$sVHw(hZUT*#ix;LZ}ePFrd)n
UtL%-8YLmk`G#ULSH*%N*05R7}TmS$7

diff --git a/test/tools/dsymutil/Inputs/submodules/Parent.pcm b/test/tools/dsymutil/Inputs/submodules/Parent.pcm
index dca33af4268d83f58cb316342eb551485cb89d18..e6909d7afa5e3c2801623df405f418a7ff572900 100644
GIT binary patch
delta 1323
zcmZ{ke`s4(6vxladrPv|CNFRKBi*a`n#Q#&ZTcf!O`0}M_N?eY2{HxOmcC@It}N*<
z)8WRTNm^yhB9U8hWgDpLAEFMT=^teln>G`5R7|0;v4569yQzOj@ds2G&U=%aDT7|#
zd-vYYIp=%NJ@@jG*U=Z>qNGop>w`ku=8OGY-}^7WS6<fpALZ~0FJV2B%_XWY8sPzU
zqb||He0vz>gZMo1iX#j&3jINR`+vBeaf0hKUhyLHeu3e4gZPZbYu<cJWCQ=8>3T%%
z%y|P>a9w6S+ewM;;32L{tbdGFhVV7cD+U-YrQr)<1Md~jGW;Y{4u|kDzHRSJ2mldu
zDLu#QYSBgfalPH<b~@V*%C+I}sYqjVd}8>d+|ufHwzM1ssNQ?H;%d(+e80YP@)(KR
zx7jTe6?p_a&@t~5z)xAR?t}v&q>+K2!NQsXI~ZzXv2;Y!VNI`rnEqT$&?i)|6~s#x
z(&L|a^JEM?aaT5N<&A%m+~)o7nBG!#%c?G#)7}NscE-4s({2jJ-$zZq<c(ti-7wGx
zK!1JzTDD_W`BM8wlW9xVInNS7KS`*x835~fn~q!uh0j>73QGufR-{|2o|MwLpt#qv
zQu44Xr?@7UkS8_Oxsa6}BwQOxdx~=}#y#^>o=+9mV!UIP^UNx)HO0LYcM-T0mlju~
zl+u1KE6s48=_${pth5%F@^LBS&ue`GkA%e)D_ONzgDZNzO8nUjjSfN*03t~;q)k>m
z7kEBk0QIl_Rrv<$j*Lc6J5GQ-xBBby^aq@BVkkU7=B+#N?D91J#_^PWy-B_EVo_3k
zso3XPPwQD_0XUuh+p&c-xtloORM~t%MUb!vwY;Ib=uRtE2k;Exp`+&7);%PQl&YLY
z2Lay34b9a@IV$FR2r`N3h>Q$Oga;djhL49Q1_s~s5|e{CR1ZZ)N5-SFjiqTbJR)o(
zHUpJ;x*YNv(&L%t@2tDs$MngT2-@Ac?X=glZOk7j`-q;Zkh%Zak3er@p(UcSRj++z
z53JW&ZX8Eo96;cE9YN+R4Or5+y=MX?ajNG~O$9)VM$n(Y*K|Nn=e4o#uUWygP@Kc(
z4@F$oTX_h<^5x&o5Ch}X@G2db4oN62PYOz~kGvY(-1`RN$@fFlnr`U3qCp4ndcRxH
z#>yau0>SaY;V6LJiubDrs-Lxjp&&*g?~%78TtkE%jfENZs7H1!3cjq4@%~S4-@;<>
GpML@Wf+++5

delta 1200
zcmZ{iUr19?9LIm>?&PkEw!39u-Bni|HN|wss;%j~b~6n6Gopx6X;&vGZDz|!MdY3H
zK`Lr;>LG|i^q~g}%N|Aya;%6VD5!@BAM7ED2$Kr(A**wD?<xX++;e}w^ZEULhwu3_
z{s<)>qNHeBXn~x~Va+eJ4DY+Rtf%=eHINME35x`4p0ZjJg2apJZ720w-9cxNoI`%w
z%lup~&IZYwe{khrT*3Hlzx3*zI{q9ary0MsNmr*+@Q^1={U7Skv4^ZQ)LX-PZJxG}
zE<?R7`5#qea^K*$-P3Vi#+Xb@*l(NB@oIhL7cx1FHy6&y07ylXSFzEFE|ZZ;N2$l{
z-CQm>!{NS2b#FA*eN@=!rff?&Kw07ZmFd_i^1iaJ{}63kKHbP^D`Er~Xv{$a&{z#r
z<J8k{P$L>(lrPRhH9<|(Rph&JP!Rxz6qbz(Y=OXNGII&-M_ypAzj%T(e+igpMGLsL
ztqRR6#=g0weWEeKndiXrDPWF>=C^|7d(u418DldAJ@f-m#PLk+Gs#<Y)Mfb^Fh^Zk
zqpFn3RE6i{C?n3O0^r&XyY84WJiyv?d_&scdnNfUXKT}_e9%xgnC<5$48GTrFP*6#
zlIq3`zGQ+=Nn2Bit%C_ZDS0WpmgR>i$?~Z<pGLm1geRTxOh}$o)|<}QQ)o>J*>N}E
z1`gu<h4`Nn7-eyZ?SmDntEj3005jFqR*)>&5oijSI^|c1si#P4>g)=Ksye|@nYn3<
zUtuH1La}hii7L%UWV+X!4Y&nq$FLwi*sX7HkLJ~6NfE%I$raV_5TiUNKV0^j)DZ*&
zMVu3x8uMjre+9rn%G>r^o$e*Hjo#!kwOa-_Lw44b)iUa0;#Cl6Ppu|kLsxfuI2P(S
z;iswVbd+^PdX7bVg;GfqUTOkZU}hLHRr9!bv1d1VV`Bs@o^`k#>(`B6zuTt1Ep-g^
z3dL-}0SxCWxQ}fJs@f4ug%AjL$l2x?QpmUFP3x(4k=DXqI&P?ediQ6gy2Hg_xu?xx
zbPXnf7W)!WO%iMCB_gzj33r4(@5zzYQ3lybW6;ZCg#`r#<Y-5CFMxw17lZ4_bg*$z
S$;2xk$7hCby(72fpT7azqY5Md

diff --git a/test/tools/dsymutil/X86/submodules.m b/test/tools/dsymutil/X86/submodules.m
index 64efc2f54ba..4cb5bcfaee2 100644
--- a/test/tools/dsymutil/X86/submodules.m
+++ b/test/tools/dsymutil/X86/submodules.m
@@ -4,9 +4,13 @@
      module Child {
        header "Child.h"
      }
+     module Empty {
+       header "Empty.h"
+     }
    }
 EOF
    clang -D CHILD_H -E -o Child.h submodules.m
+   touch empty.h
    clang -cc1 -emit-obj -fmodules -fmodule-map-file=modules.modulemap \
      -fmodule-format=obj -g -dwarf-ext-refs -fmodules-cache-path=. \
      -fdisable-module-hash submodules.m -o 1.o
@@ -19,6 +23,7 @@ EOF
 // ---------------------------------------------------------------------
 #ifdef CHILD_H
 // ---------------------------------------------------------------------
+
 // CHECK:            DW_TAG_compile_unit
 // CHECK-NOT:        DW_TAG
 // CHECK:              DW_TAG_module
@@ -28,13 +33,22 @@ EOF
 // CHECK:                  DW_TAG_structure_type
 // CHECK-NOT:                DW_TAG
 // CHECK:                    DW_AT_name {{.*}}"PruneMeNot"
-
 struct PruneMeNot;
 
 // ---------------------------------------------------------------------
 #else
 // ---------------------------------------------------------------------
 
+// CHECK:            DW_TAG_compile_unit
+// CHECK:              DW_TAG_module
+// CHECK-NEXT:           DW_AT_name{{.*}}"Parent"
+// CHECK:              DW_TAG_module
+// CHECK-NEXT:           DW_AT_name{{.*}}"Child"
+// CHECK: 0x0[[EMPTY:.*]]: DW_TAG_module
+// CHECK-NEXT:             DW_AT_name{{.*}}"Empty"
+
+// CHECK:     DW_AT_import  {{.*}}0x{{0*}}[[EMPTY]]
 @import Parent.Child;
+@import Parent.Empty;
 int main(int argc, char **argv) { return 0; }
 #endif
diff --git a/tools/dsymutil/DwarfLinker.cpp b/tools/dsymutil/DwarfLinker.cpp
index c877264a067..52c480ec4f1 100644
--- a/tools/dsymutil/DwarfLinker.cpp
+++ b/tools/dsymutil/DwarfLinker.cpp
@@ -1807,6 +1807,9 @@ static bool analyzeContextInfo(const DWARFDebugInfoEntryMinimal *DIE,
                 DIE->getAttributeValueAsUnsignedConstant(
                     &CU.getOrigUnit(), dwarf::DW_AT_declaration, 0);
 
+  // Don't prune it if there is no definition for the DIE.
+  Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
+
   return Info.Prune;
 }
 
@@ -3338,21 +3341,23 @@ bool DwarfLinker::link(const DebugMap &Map) {
     DWARFContextInMemory DwarfContext(*ErrOrObj);
     startDebugObject(DwarfContext, *Obj);
 
-    // In a first phase, just read in the debug info and store the DIE
-    // parent links that we will use during the next phase.
+    // In a first phase, just read in the debug info and load all clang modules.
     for (const auto &CU : DwarfContext.compile_units()) {
       auto *CUDie = CU->getUnitDIE(false);
       if (Options.Verbose) {
         outs() << "Input compilation unit:";
         CUDie->dump(outs(), CU.get(), 0);
       }
-      if (!registerModuleReference(*CUDie, *CU, ModuleMap)) {
+
+      if (!registerModuleReference(*CUDie, *CU, ModuleMap))
         Units.emplace_back(*CU, UnitID++, !Options.NoODR, "");
-        analyzeContextInfo(CUDie, 0, Units.back(), &ODRContexts.getRoot(),
-                           StringPool, ODRContexts);
-      }
     }
 
+    // Now build the DIE parent links that we will use during the next phase.
+    for (auto &CurrentUnit : Units)
+      analyzeContextInfo(CurrentUnit.getOrigUnit().getUnitDIE(), 0, CurrentUnit,
+                         &ODRContexts.getRoot(), StringPool, ODRContexts);
+
     // Then mark all the DIEs that need to be present in the linked
     // output and collect some information about them. Note that this
     // loop can not be merged with the previous one becaue cross-cu
-- 
2.34.1