Reapply an improved version of r180816/180817.

Change the informal convention of DBG_VALUE machine instructions so that
we can express a register-indirect address with an offset of 0.
The old convention was that a DBG_VALUE is a register-indirect value if
the offset (operand 1) is nonzero. The new convention is that a DBG_VALUE
is register-indirect if the first operand is a register and the second
operand is an immediate. For plain register values the combination reg,
reg is used. MachineInstrBuilder::BuildMI knows how to build the new
DBG_VALUES.

rdar://problem/13658587

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185966 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 115 insertions, 5 deletions

diff --git a/test/DebugInfo/X86/op_deref.ll b/test/DebugInfo/X86/op_deref.ll
index c3580a790c..fc9aab16ea 100644
--- a/test/DebugInfo/X86/op_deref.ll
+++ b/test/DebugInfo/X86/op_deref.ll
@@ -1,10 +1,16 @@
 ; RUN: llc -O0 -mtriple=x86_64-apple-darwin %s -o %t -filetype=obj
-; RUN: llvm-dwarfdump -debug-dump=info %t | FileCheck %s
+; RUN: llvm-dwarfdump -debug-dump=info %t | FileCheck %s -check-prefix=DW-CHECK
 
-; CHECK: DW_AT_name [DW_FORM_strp]  ( .debug_str[0x00000067] = "vla")
+; DW-CHECK: DW_AT_name [DW_FORM_strp]  ( .debug_str[0x00000067] = "vla")
 ; FIXME: The location here needs to be fixed, but llvm-dwarfdump doesn't handle
 ; DW_AT_location lists yet.
-; CHECK: DW_AT_location [DW_FORM_data4]                      (0x00000000)
+; DW-CHECK: DW_AT_location [DW_FORM_data4]                      (0x00000000)
+
+; Unfortunately llvm-dwarfdump can't unparse a list of DW_AT_locations
+; right now, so we check the asm output:
+; RUN: llc -O0 -mtriple=x86_64-apple-darwin %s -o - -filetype=asm | FileCheck %s -check-prefix=ASM-CHECK
+; vla should have a register-indirect address at one point.
+; ASM-CHECK: DEBUG_VALUE: vla <- [RCX+0]
 
 define void @testVLAwithSize(i32 %s) nounwind uwtable ssp {
 entry:
diff --git a/test/DebugInfo/X86/parameters.ll b/test/DebugInfo/X86/parameters.ll
index 6834f4b0d2..78469243b3 100644
--- a/test/DebugInfo/X86/parameters.ll
+++ b/test/DebugInfo/X86/parameters.ll
@@ -24,9 +24,9 @@
 
 ; CHECK: debug_info contents
 ; CHECK: DW_AT_name{{.*}} = "f"
-; 0x74 is DW_OP_breg0 + 4, showing that the parameter is accessed indirectly
+; 0x74 is DW_OP_breg4, showing that the parameter is accessed indirectly
 ; (with a zero offset) from the register parameter
-; CHECK: DW_AT_location{{.*}}(<0x02> 74 00 )
+; CHECK: DW_AT_location{{.*}}(<0x0{{.}}> 74 00
 
 ; CHECK: DW_AT_name{{.*}} = "g"
 ; CHECK: DW_AT_location{{.*}}([[G_LOC:0x[0-9]*]])
diff --git a/test/DebugInfo/X86/vla.ll b/test/DebugInfo/X86/vla.ll
new file mode 100644
index 0000000000..81faec70b7
--- /dev/null
+++ b/test/DebugInfo/X86/vla.ll
@@ -0,0 +1,104 @@
+; RUN: llc -O0 -mtriple=x86_64-apple-darwin -filetype=asm %s -o - | FileCheck %s
+; Ensure that we generate a breg+0 location for the variable length array a.
+; CHECK: ##DEBUG_VALUE: vla:a <- [RDX+0]
+; rdar://problem/13658587
+;
+; generated from:
+;
+; int vla(int n) {
+;   int a[n];
+;   a[0] = 42;
+;   return a[n-1];
+; }
+;
+; int main(int argc, char** argv) {
+;    return vla(argc);
+; }
+
+; ModuleID = 'vla.c'
+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-apple-macosx10.8.0"
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @vla(i32 %n) nounwind ssp uwtable {
+entry:
+  %n.addr = alloca i32, align 4
+  %saved_stack = alloca i8*
+  %cleanup.dest.slot = alloca i32
+  store i32 %n, i32* %n.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %n.addr}, metadata !15), !dbg !16
+  %0 = load i32* %n.addr, align 4, !dbg !17
+  %1 = zext i32 %0 to i64, !dbg !17
+  %2 = call i8* @llvm.stacksave(), !dbg !17
+  store i8* %2, i8** %saved_stack, !dbg !17
+  %vla = alloca i32, i64 %1, align 16, !dbg !17
+  call void @llvm.dbg.declare(metadata !{i32* %vla}, metadata !18), !dbg !17
+  %arrayidx = getelementptr inbounds i32* %vla, i64 0, !dbg !22
+  store i32 42, i32* %arrayidx, align 4, !dbg !22
+  %3 = load i32* %n.addr, align 4, !dbg !23
+  %sub = sub nsw i32 %3, 1, !dbg !23
+  %idxprom = sext i32 %sub to i64, !dbg !23
+  %arrayidx1 = getelementptr inbounds i32* %vla, i64 %idxprom, !dbg !23
+  %4 = load i32* %arrayidx1, align 4, !dbg !23
+  store i32 1, i32* %cleanup.dest.slot
+  %5 = load i8** %saved_stack, !dbg !24
+  call void @llvm.stackrestore(i8* %5), !dbg !24
+  ret i32 %4, !dbg !23
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+; Function Attrs: nounwind
+declare i8* @llvm.stacksave() nounwind
+
+; Function Attrs: nounwind
+declare void @llvm.stackrestore(i8*) nounwind
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @main(i32 %argc, i8** %argv) nounwind ssp uwtable {
+entry:
+  %retval = alloca i32, align 4
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 8
+  store i32 0, i32* %retval
+  store i32 %argc, i32* %argc.addr, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %argc.addr}, metadata !25), !dbg !26
+  store i8** %argv, i8*** %argv.addr, align 8
+  call void @llvm.dbg.declare(metadata !{i8*** %argv.addr}, metadata !27), !dbg !26
+  %0 = load i32* %argc.addr, align 4, !dbg !28
+  %call = call i32 @vla(i32 %0), !dbg !28
+  ret i32 %call, !dbg !28
+}
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang version 3.3 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/vla.c] [DW_LANG_C99]
+!1 = metadata !{metadata !"vla.c", metadata !""}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4, metadata !9}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"vla", metadata !"vla", metadata !"", i32 1, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @vla, null, null, metadata !2, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [vla]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/vla.c]
+!6 = metadata !{i32 786453, i32 0, i32 0, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{metadata !8, metadata !8}
+!8 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"main", metadata !"main", metadata !"", i32 7, metadata !10, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32, i8**)* @main, null, null, metadata !2, i32 7} ; [ DW_TAG_subprogram ] [line 7] [def] [main]
+!10 = metadata !{i32 786453, i32 0, i32 0, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !11, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!11 = metadata !{metadata !8, metadata !8, metadata !12}
+!12 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !13} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
+!13 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !14} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from char]
+!14 = metadata !{i32 786468, null, null, metadata !"char", i32 0, i64 8, i64 8, i64 0, i32 0, i32 6} ; [ DW_TAG_base_type ] [char] [line 0, size 8, align 8, offset 0, enc DW_ATE_signed_char]
+!15 = metadata !{i32 786689, metadata !4, metadata !"n", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [n] [line 1]
+!16 = metadata !{i32 1, i32 0, metadata !4, null}
+!17 = metadata !{i32 2, i32 0, metadata !4, null}
+!18 = metadata !{i32 786688, metadata !4, metadata !"a", metadata !5, i32 2, metadata !19, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [a] [line 2]
+!19 = metadata !{i32 786433, null, null, metadata !"", i32 0, i64 0, i64 32, i32 0, i32 0, metadata !8, metadata !20, i32 0, i32 0} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
+!20 = metadata !{metadata !21}
+!21 = metadata !{i32 786465, i64 0, i64 -1}       ; [ DW_TAG_subrange_type ] [unbounded]
+!22 = metadata !{i32 3, i32 0, metadata !4, null}
+!23 = metadata !{i32 4, i32 0, metadata !4, null}
+!24 = metadata !{i32 5, i32 0, metadata !4, null}
+!25 = metadata !{i32 786689, metadata !9, metadata !"argc", metadata !5, i32 16777223, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [argc] [line 7]
+!26 = metadata !{i32 7, i32 0, metadata !9, null}
+!27 = metadata !{i32 786689, metadata !9, metadata !"argv", metadata !5, i32 33554439, metadata !12, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [argv] [line 7]
+!28 = metadata !{i32 8, i32 0, metadata !9, null}