DebugInfo+DeadArgElimination: Ensure llvm::Function*s from debug info are updated...

After some stellar (& inspired) help from Reid Kleckner providing a test
case for some rather unstable undefined behavior showing up as
assertions produced by r214761, I was able to fix this issue in DAE
involving the application of both varargs removal, followed by normal
argument removal.

Indeed I introduced this same bug into ArgumentPromotion (r212128) by
copying the code from DAE, and when I fixed the bug in ArgPromo
(r213805) and commented in that patch that I didn't need to address the
same issue in DAE because it was a single pass. Turns out it's two pass,
one for the varargs and one for the normal arguments, so the same fix is
needed (at least during varargs removal). So here it is.

(the observable/net effect of this bug, even when it didn't result in
assertion failure, is that debug info would describe the DAE'd function
in the abstract, but wouldn't provide high/low_pc, variable locations,
line table, etc (it would appear as though the function had been
entirely optimized away), see the original PR14016 for details of the
general problem)

I'm not recommitting the assertion just yet, as there's been another
regression of it since I last tried. It might just be a few test cases
weren't adequately updated after Adrian or Duncan's recent schema
changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219210 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/ArgumentPromotion.cpp b/lib/Transforms/IPO/ArgumentPromotion.cpp
index 5934619b4c18e1b30cba137c758759c4c514ce34..a1d66726881d2f8aed17d7ac8bc7d8f2bfaebc04 100644 (file)
--- a/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -703,6 +703,8 @@ CallGraphNode *ArgPromotion::DoPromotion(Function *F,
   if (DI != FunctionDIs.end()) {
     DISubprogram SP = DI->second;
     SP.replaceFunction(NF);
+    // Ensure the map is updated so it can be reused on subsequent argument
+    // promotions of the same function.
     FunctionDIs.erase(DI);
     FunctionDIs[NF] = SP;
   }

diff --git a/lib/Transforms/IPO/DeadArgumentElimination.cpp b/lib/Transforms/IPO/DeadArgumentElimination.cpp
index da4f0326f19b65c7d481c6abe19a95d8e33aa777..4045c09aaa2bf64bea01e0768427144c1d71fe14 100644 (file)
--- a/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -302,8 +302,14 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
 
   // Patch the pointer to LLVM function in debug info descriptor.
   auto DI = FunctionDIs.find(&Fn);
-  if (DI != FunctionDIs.end())
-    DI->second.replaceFunction(NF);
+  if (DI != FunctionDIs.end()) {
+    DISubprogram SP = DI->second;
+    SP.replaceFunction(NF);
+    // Ensure the map is updated so it can be reused on non-varargs argument
+    // eliminations of the same function.
+    FunctionDIs.erase(DI);
+    FunctionDIs[NF] = SP;
+  }
 
   // Fix up any BlockAddresses that refer to the function.
   Fn.replaceAllUsesWith(ConstantExpr::getBitCast(NF, Fn.getType()));

diff --git a/test/Transforms/DeadArgElim/dbginfo.ll b/test/Transforms/DeadArgElim/dbginfo.ll
index 3f282bb5762d1f11ebc59336150e33c954bd45b3..b457f0130f89bfdcf38fc52fa7a411797f5ca131 100644 (file)
--- a/test/Transforms/DeadArgElim/dbginfo.ll
+++ b/test/Transforms/DeadArgElim/dbginfo.ll
@@ -1,65 +1,70 @@
 ; RUN: opt -deadargelim -S < %s | FileCheck %s
 ; PR14016
 
-; Check that debug info metadata for subprograms stores pointers to
-; updated LLVM functions.
+; Built with clang (then manually running -mem2reg with opt) from the following source:
+; static void f1(int, ...) {
+; }
+;
+; void f2() {
+;   f1(1);
+; }
 
-target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
-target triple = "x86_64-unknown-linux-gnu"
+; Test both varargs removal and removal of a traditional dead arg together, to
+; test both the basic functionality, and a particular wrinkle involving updating
+; the function->debug info mapping on update to ensure it's accurate when used
+; again for the next removal.
 
-@x = global i32 0, align 4
+; CHECK: void ()* @_ZL2f1iz, {{.*}} ; [ DW_TAG_subprogram ] {{.*}} [f1]
 
-define void @_Z3runv() uwtable {
-entry:
-  call void @_ZN12_GLOBAL__N_18dead_argEPv(i8* null), !dbg !10
-  call void (...)* @_ZN12_GLOBAL__N_111dead_varargEz(), !dbg !12
-  ret void, !dbg !13
-}
+; Check that debug info metadata for subprograms stores pointers to
+; updated LLVM functions.
 
-; Argument will be deleted
-define internal void @_ZN12_GLOBAL__N_18dead_argEPv(i8* %foo) nounwind uwtable {
+; Function Attrs: uwtable
+define void @_Z2f2v() #0 {
 entry:
-  %0 = load i32* @x, align 4, !dbg !14
-  %inc = add nsw i32 %0, 1, !dbg !14
-  store i32 %inc, i32* @x, align 4, !dbg !14
+  call void (i32, ...)* @_ZL2f1iz(i32 1), !dbg !15
   ret void, !dbg !16
 }
 
-; Vararg will be deleted
-define internal void @_ZN12_GLOBAL__N_111dead_varargEz(...) nounwind uwtable {
+; Function Attrs: nounwind uwtable
+define internal void @_ZL2f1iz(i32, ...) #1 {
 entry:
-  %0 = load i32* @x, align 4, !dbg !17
-  %inc = add nsw i32 %0, 1, !dbg !17
-  store i32 %inc, i32* @x, align 4, !dbg !17
-  ret void, !dbg !19
+  call void @llvm.dbg.value(metadata !{i32 %0}, i64 0, metadata !17, metadata !18), !dbg !19
+  ret void, !dbg !20
 }
 
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!21}
-
-!0 = metadata !{metadata !"0x11\004\00clang version 3.2 (trunk 165305)\000\00\000\00\000", metadata !20, metadata !1, metadata !1, metadata !3, metadata !1,  metadata !1} ; [ DW_TAG_compile_unit ] [/home/samsonov/tmp/clang-di/test.cc] [DW_LANG_C_plus_plus]
-!1 = metadata !{i32 0}
-!3 = metadata !{metadata !5, metadata !8, metadata !9}
-!5 = metadata !{metadata !"0x2e\00run\00run\00\008\000\001\000\006\00256\000\008", metadata !20, metadata !6, metadata !7, null, void ()* @_Z3runv, null, null, metadata !1} ; [ DW_TAG_subprogram ] [line 8] [def] [run]
-!6 = metadata !{metadata !"0x29", metadata !20} ; [ DW_TAG_file_type ]
-!7 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", i32 0, null, null, metadata !1, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
-!8 = metadata !{metadata !"0x2e\00dead_vararg\00dead_vararg\00\005\001\001\000\006\00256\000\005", metadata !20, metadata !6, metadata !7, null, void (...)* @_ZN12_GLOBAL__N_111dead_varargEz, null, null, metadata !1} ; [ DW_TAG_subprogram ] [line 5] [local] [def] [dead_vararg]
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
 
-; CHECK: metadata !"0x2e\00dead_vararg\00{{[^"]+}}"{{.*}}void ()* @_ZN12_GLOBAL__N_111dead_varargEz
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #2
 
-!9 = metadata !{metadata !"0x2e\00dead_arg\00dead_arg\00\004\001\001\000\006\00256\000\004", metadata !20, metadata !6, metadata !7, null, void (i8*)* @_ZN12_GLOBAL__N_18dead_argEPv, null, null, metadata !1} ; [ DW_TAG_subprogram ] [line 4] [local] [def] [dead_arg]
+attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readnone }
 
-; CHECK: metadata !"0x2e\00dead_arg\00{{[^"]+}}"{{.*}}void ()* @_ZN12_GLOBAL__N_18dead_argEPv
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!12, !13}
+!llvm.ident = !{!14}
 
-!10 = metadata !{i32 8, i32 14, metadata !11, null}
-!11 = metadata !{metadata !"0xb\008\0012\000", metadata !20, metadata !5} ; [ DW_TAG_lexical_block ] [/home/samsonov/tmp/clang-di/test.cc]
-!12 = metadata !{i32 8, i32 27, metadata !11, null}
-!13 = metadata !{i32 8, i32 42, metadata !11, null}
-!14 = metadata !{i32 4, i32 28, metadata !15, null}
-!15 = metadata !{metadata !"0xb\004\0026\002", metadata !20, metadata !9} ; [ DW_TAG_lexical_block ] [/home/samsonov/tmp/clang-di/test.cc]
-!16 = metadata !{i32 4, i32 33, metadata !15, null}
-!17 = metadata !{i32 5, i32 25, metadata !18, null}
-!18 = metadata !{metadata !"0xb\005\0023\001", metadata !20, metadata !8} ; [ DW_TAG_lexical_block ] [/home/samsonov/tmp/clang-di/test.cc]
-!19 = metadata !{i32 5, i32 30, metadata !18, null}
-!20 = metadata !{metadata !"test.cc", metadata !"/home/samsonov/tmp/clang-di"}
-!21 = metadata !{i32 1, metadata !"Debug Info Version", i32 2}
+!0 = metadata !{metadata !"0x11\004\00clang version 3.6.0 \000\00\000\00\001", metadata !1, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2} ; [ DW_TAG_compile_unit ] [/tmp/dbginfo/dbg.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"dbg.cpp", metadata !"/tmp/dbginfo"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4, metadata !8}
+!4 = metadata !{metadata !"0x2e\00f2\00f2\00_Z2f2v\004\000\001\000\000\00256\000\004", metadata !1, metadata !5, metadata !6, null, void ()* @_Z2f2v, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 4] [def] [f2]
+!5 = metadata !{metadata !"0x29", metadata !1}    ; [ DW_TAG_file_type ] [/tmp/dbginfo/dbg.cpp]
+!6 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !7, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{null}
+!8 = metadata !{metadata !"0x2e\00f1\00f1\00_ZL2f1iz\001\001\001\000\000\00256\000\001", metadata !1, metadata !5, metadata !9, null, void (i32, ...)* @_ZL2f1iz, null, null, metadata !2} ; [ DW_TAG_subprogram ] [line 1] [local] [def] [f1]
+!9 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !10, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!10 = metadata !{null, metadata !11, null}
+!11 = metadata !{metadata !"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!12 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!13 = metadata !{i32 2, metadata !"Debug Info Version", i32 2}
+!14 = metadata !{metadata !"clang version 3.6.0 "}
+!15 = metadata !{i32 5, i32 3, metadata !4, null}
+!16 = metadata !{i32 6, i32 1, metadata !4, null}
+!17 = metadata !{metadata !"0x101\00\0016777217\000", metadata !8, metadata !5, metadata !11} ; [ DW_TAG_arg_variable ] [line 1]
+!18 = metadata !{metadata !"0x102"}               ; [ DW_TAG_expression ]
+!19 = metadata !{i32 1, i32 19, metadata !8, null}
+!20 = metadata !{i32 2, i32 1, metadata !8, null}