Move the complex address expression out of DIVariable and into an extra

argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.
llvm-svn: 218787

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/test/Transforms/SampleProfile/branch.ll b/llvm/test/Transforms/SampleProfile/branch.ll
index 65f1f176993..693a40c4343 100644
--- a/llvm/test/Transforms/SampleProfile/branch.ll
+++ b/llvm/test/Transforms/SampleProfile/branch.ll
@@ -32,8 +32,8 @@ define i32 @main(i32 %argc, i8** nocapture readonly %argv) #0 {
 ; CHECK: Printing analysis 'Branch Probability Analysis' for function 'main':
 
 entry:
-  tail call void @llvm.dbg.value(metadata !{i32 %argc}, i64 0, metadata !13), !dbg !27
-  tail call void @llvm.dbg.value(metadata !{i8** %argv}, i64 0, metadata !14), !dbg !27
+  tail call void @llvm.dbg.value(metadata !{i32 %argc}, i64 0, metadata !13, metadata !{}), !dbg !27
+  tail call void @llvm.dbg.value(metadata !{i8** %argv}, i64 0, metadata !14, metadata !{}), !dbg !27
   %cmp = icmp slt i32 %argc, 2, !dbg !28
   br i1 %cmp, label %return, label %if.end, !dbg !28
 ; CHECK: edge entry -> return probability is 1 / 2 = 50%
@@ -43,7 +43,7 @@ if.end:                                           ; preds = %entry
   %arrayidx = getelementptr inbounds i8** %argv, i64 1, !dbg !30
   %0 = load i8** %arrayidx, align 8, !dbg !30, !tbaa !31
   %call = tail call i32 @atoi(i8* %0) #4, !dbg !30
-  tail call void @llvm.dbg.value(metadata !{i32 %call}, i64 0, metadata !17), !dbg !30
+  tail call void @llvm.dbg.value(metadata !{i32 %call}, i64 0, metadata !17, metadata !{}), !dbg !30
   %cmp1 = icmp sgt i32 %call, 100, !dbg !35
   br i1 %cmp1, label %for.body, label %if.end6, !dbg !35
 ; CHECK: edge if.end -> for.body probability is 1 / 2 = 50%
@@ -55,14 +55,14 @@ for.body:                                         ; preds = %if.end, %for.body
   %add = fadd double %s.015, 3.049000e+00, !dbg !36
   %conv = sitofp i32 %u.016 to double, !dbg !36
   %add4 = fadd double %add, %conv, !dbg !36
-  tail call void @llvm.dbg.value(metadata !{double %add4}, i64 0, metadata !18), !dbg !36
+  tail call void @llvm.dbg.value(metadata !{double %add4}, i64 0, metadata !18, metadata !{}), !dbg !36
   %div = fdiv double 3.940000e+00, %s.015, !dbg !37
   %mul = fmul double %div, 3.200000e-01, !dbg !37
   %add5 = fadd double %add4, %mul, !dbg !37
   %sub = fsub double %add4, %add5, !dbg !37
-  tail call void @llvm.dbg.value(metadata !{double %sub}, i64 0, metadata !18), !dbg !37
+  tail call void @llvm.dbg.value(metadata !{double %sub}, i64 0, metadata !18, metadata !{}), !dbg !37
   %inc = add nsw i32 %u.016, 1, !dbg !38
-  tail call void @llvm.dbg.value(metadata !{i32 %inc}, i64 0, metadata !21), !dbg !38
+  tail call void @llvm.dbg.value(metadata !{i32 %inc}, i64 0, metadata !21, metadata !{}), !dbg !38
   %exitcond = icmp eq i32 %inc, %call, !dbg !38
   br i1 %exitcond, label %if.end6, label %for.body, !dbg !38
 ; CHECK: edge for.body -> if.end6 probability is 1 / 10227 = 0.00977804
@@ -86,7 +86,7 @@ declare i32 @atoi(i8* nocapture) #1
 declare i32 @printf(i8* nocapture readonly, ...) #2
 
 ; Function Attrs: nounwind readnone
-declare void @llvm.dbg.value(metadata, i64, metadata) #3
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #3
 
 attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "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 readonly "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }