DWARFExpression: Fix/add support for (v4) debug_loc base address selection entries

The DWARFExpression is parsing the location lists in about five places.
Of those, only one actually had proper support for base address
selection entries.

Since r374600, llvm has started to produce location expressions with
base address selection entries more aggresively, which caused some tests
to fail.

This patch adds support for these entries to the places which had it
missing, fixing the failing tests. It also adds a targeted test for the
two of the three fixes, which should continue testing this functionality
even if the llvm output changes. I am not aware of a way to write a
targeted test for the third fix (DWARFExpression::Evaluate).

llvm-svn: 374769

2 files changed, 47 insertions, 12 deletions

diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index d1ef9572685..3789d914773 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -636,6 +636,11 @@ bool DWARFExpression::LocationListContainsAddress(
       if (lo_pc == 0 && hi_pc == 0)
         break;
 
+      if ((m_data.GetAddressByteSize() == 4 && (lo_pc == UINT32_MAX)) ||
+          (m_data.GetAddressByteSize() == 8 && (lo_pc == UINT64_MAX))) {
+        loclist_base_addr = hi_pc + m_loclist_slide;
+        continue;
+      }
       lo_pc += loclist_base_addr - m_loclist_slide;
       hi_pc += loclist_base_addr - m_loclist_slide;
 
@@ -671,6 +676,12 @@ bool DWARFExpression::GetLocation(addr_t base_addr, addr_t pc,
       if (lo_pc == 0 && hi_pc == 0)
         break;
 
+      if ((m_data.GetAddressByteSize() == 4 && (lo_pc == UINT32_MAX)) ||
+          (m_data.GetAddressByteSize() == 8 && (lo_pc == UINT64_MAX))) {
+        curr_base_addr = hi_pc + m_loclist_slide;
+        continue;
+      }
+
       lo_pc += curr_base_addr - m_loclist_slide;
       hi_pc += curr_base_addr - m_loclist_slide;
 
@@ -967,6 +978,13 @@ bool DWARFExpression::Evaluate(ExecutionContext *exe_ctx,
         if (lo_pc == 0 && hi_pc == 0)
           break;
 
+        if ((m_data.GetAddressByteSize() == 4 &&
+             (lo_pc == UINT32_MAX)) ||
+            (m_data.GetAddressByteSize() == 8 &&
+             (lo_pc == UINT64_MAX))) {
+          curr_loclist_base_load_addr = hi_pc + m_loclist_slide;
+          continue;
+        }
         lo_pc += curr_loclist_base_load_addr - m_loclist_slide;
         hi_pc += curr_loclist_base_load_addr - m_loclist_slide;
 
diff --git a/lldb/test/Shell/SymbolFile/DWARF/debug_loc.s b/lldb/test/Shell/SymbolFile/DWARF/debug_loc.s
index 8dec979f694..bc9c44db4c0 100644
--- a/lldb/test/Shell/SymbolFile/DWARF/debug_loc.s
+++ b/lldb/test/Shell/SymbolFile/DWARF/debug_loc.s
@@ -17,14 +17,22 @@
 # CHECK: Variable: {{.*}}, name = "x0", type = "int", location = DW_OP_reg0 RAX,
 # CHECK: Variable: {{.*}}, name = "x1", type = "int", location = ,
 # CHECK: Variable: {{.*}}, name = "x2", type = "int", location = ,
+# CHECK: Variable: {{.*}}, name = "x3", type = "int", location = DW_OP_reg1 RDX,
 
         .type   f,@function
 f:                                      # @f
 .Lfunc_begin0:
-        movl    %edi, %eax
+        nop
 .Ltmp0:
-        retq
+        nop
 .Ltmp1:
+        nop
+.Ltmp2:
+        nop
+.Ltmp3:
+        nop
+.Ltmp4:
+        nop
 .Lfunc_end0:
         .size   f, .Lfunc_end0-f
 
@@ -35,12 +43,6 @@ f:                                      # @f
         .asciz  "f"
 .Linfo_string4:
         .asciz  "int"
-.Lx0:
-        .asciz  "x0"
-.Lx1:
-        .asciz  "x1"
-.Lx2:
-        .asciz  "x2"
 
         .section        .debug_loc,"",@progbits
 .Ldebug_loc0:
@@ -54,6 +56,17 @@ f:                                      # @f
         .byte   80                      # super-register DW_OP_reg0
         .quad   0
         .quad   0
+
+.Ldebug_loc3:
+        .quad   -1                      # Select base address
+        .quad   .Ltmp1
+        .quad   .Ltmp1-.Ltmp1
+        .quad   .Ltmp2-.Ltmp1
+        .short  1                       # Loc expr size
+        .byte   81                      # super-register DW_OP_reg1
+        .quad   0
+        .quad   0
+
 .Ldebug_loc2:
         .quad   .Lfunc_begin0-.Lfunc_begin0
         .quad   .Lfunc_end0-.Lfunc_begin0
@@ -88,7 +101,7 @@ f:                                      # @f
         .byte   2                       # DW_AT_location
         .byte   23                      # DW_FORM_sec_offset
         .byte   3                       # DW_AT_name
-        .byte   14                      # DW_FORM_strp
+        .byte   8                       # DW_FORM_string
         .byte   73                      # DW_AT_type
         .byte   19                      # DW_FORM_ref4
         .byte   0                       # EOM(1)
@@ -123,15 +136,19 @@ f:                                      # @f
         .long   .Lint                   # DW_AT_type
         .byte   3                       # Abbrev [3] DW_TAG_formal_parameter
         .long   .Ldebug_loc0            # DW_AT_location
-        .long   .Lx0                    # DW_AT_name
+        .asciz  "x0"                    # DW_AT_name
         .long   .Lint-.Lcu_begin0       # DW_AT_type
         .byte   3                       # Abbrev [3] DW_TAG_formal_parameter
         .long   0xdeadbeef              # DW_AT_location
-        .long   .Lx1                    # DW_AT_name
+        .asciz  "x1"                    # DW_AT_name
         .long   .Lint-.Lcu_begin0       # DW_AT_type
         .byte   3                       # Abbrev [3] DW_TAG_formal_parameter
         .long   .Ldebug_loc2            # DW_AT_location
-        .long   .Lx2                    # DW_AT_name
+        .asciz  "x2"                    # DW_AT_name
+        .long   .Lint-.Lcu_begin0       # DW_AT_type
+        .byte   3                       # Abbrev [3] DW_TAG_formal_parameter
+        .long   .Ldebug_loc3            # DW_AT_location
+        .asciz  "x3"                    # DW_AT_name
         .long   .Lint-.Lcu_begin0       # DW_AT_type
         .byte   0                       # End Of Children Mark
 .Lint: