[DebugInfo] LowerDbgDeclare: Add derefs when handling CallInst users
LowerDbgDeclare inserts a dbg.value before each use of an address
described by a dbg.declare. When inserting a dbg.value before a CallInst
use, however, it fails to append DW_OP_deref to the DIExpression.
The DW_OP_deref is needed to reflect the fact that a dbg.value describes
a source variable directly (as opposed to a dbg.declare, which relies on
pointer indirection).
This patch adds in the DW_OP_deref where needed. This results in the
correct values being shown during a debug session for a program compiled
with ASan and optimizations (see https://reviews.llvm.org/D49520). Note
that ConvertDebugDeclareToDebugValue is already correct -- no changes
there were needed.
One complication is that SelectionDAG is unable to distinguish between
direct and indirect frame-index (FRAMEIX) SDDbgValues. This patch also
fixes this long-standing issue in order to not regress integration tests
relying on the incorrect assumption that all frame-index SDDbgValues are
indirect. This is a necessary fix: the newly-added DW_OP_derefs cannot
be lowered properly otherwise. Basically the fix prevents a direct
SDDbgValue with DIExpression(DW_OP_deref) from being dereferenced twice
by a debugger. There were a handful of tests relying on this incorrect
"FRAMEIX => indirect" assumption which actually had incorrect
DW_AT_locations: these are all fixed up in this patch.
Testing:
- check-llvm, and an end-to-end test using lldb to debug an optimized
program.
- Existing unit tests for DIExpression::appendToStack fully cover the
new DIExpression::append utility.
- check-debuginfo (the debug info integration tests)
Differential Revision: https://reviews.llvm.org/D49454
llvm-svn: 338069
diff --git a/llvm/test/DebugInfo/X86/bbjoin.ll b/llvm/test/DebugInfo/X86/bbjoin.ll
index 02b6d41..b3f20a9 100644
--- a/llvm/test/DebugInfo/X86/bbjoin.ll
+++ b/llvm/test/DebugInfo/X86/bbjoin.ll
@@ -12,7 +12,7 @@
; CHECK: ![[X:.*]] = !DILocalVariable(name: "x",
; CHECK: bb.0.entry:
; CHECK: DBG_VALUE 23, debug-use $noreg, ![[X]],
-; CHECK: DBG_VALUE debug-use $rsp, 0, ![[X]], !DIExpression(DW_OP_plus_uconst, 4, DW_OP_deref),
+; CHECK: DBG_VALUE debug-use $rsp, debug-use $noreg, ![[X]], !DIExpression(DW_OP_plus_uconst, 4, DW_OP_deref),
; CHECK: bb.1.if.then:
; CHECK: DBG_VALUE 43, debug-use $noreg, ![[X]],
; CHECK: bb.2.if.end:
diff --git a/llvm/test/DebugInfo/X86/dbg-value-const-byref.ll b/llvm/test/DebugInfo/X86/dbg-value-const-byref.ll
index 49d0ea2..945c95f 100644
--- a/llvm/test/DebugInfo/X86/dbg-value-const-byref.ll
+++ b/llvm/test/DebugInfo/X86/dbg-value-const-byref.ll
@@ -25,7 +25,7 @@
; CHECK-NEXT: [0x{{0*.*}}, 0x[[C1:.*]]): DW_OP_consts +3
; CHECK-NEXT: [0x[[C1]], 0x[[C2:.*]]): DW_OP_consts +7
; CHECK-NEXT: [0x[[C2]], 0x[[R1:.*]]): DW_OP_reg0 RAX
-; CHECK-NEXT: [0x[[R1]], 0x[[R2:.*]]): DW_OP_breg7 RSP+4, DW_OP_deref)
+; CHECK-NEXT: [0x[[R1]], 0x[[R2:.*]]): DW_OP_breg7 RSP+4)
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_name{{.*}}"i"
diff --git a/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll b/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll
index b411f20..a2cf2cc 100644
--- a/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll
+++ b/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll
@@ -20,10 +20,14 @@
}
; CHECK-LABEL: test
-; CHECK: #DEBUG_VALUE: test:w <- [DW_OP_plus_uconst 8] [$rsp+0]
+; To get the value of the variable, we need to do [$rsp+8], i.e:
+; CHECK: #DEBUG_VALUE: test:w <- [DW_OP_plus_uconst 8, DW_OP_deref] $rsp
; DWARF: DW_AT_location [DW_FORM_sec_offset] (
; DWARF-NEXT: [{{.*}}, {{.*}}): DW_OP_breg7 RSP+8)
+; Note: A previous version of this test checked for `[DW_OP_plus_uconst 8] [$rsp+0]`,
+; which is incorrect, because it adds the stack offset after dereferencing the stack pointer.
+
declare i1 @fn(i64*, i64*, i64*, i8*, i64, i64*, i32*, i8*)
declare void @llvm.dbg.value(metadata, metadata, metadata)
@@ -36,7 +40,7 @@
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = distinct !DISubprogram(name: "test", type: !10, unit: !0)
!5 = !DILocalVariable(name: "w", scope: !4, type: !9)
-!6 = !DIExpression()
+!6 = !DIExpression(DW_OP_deref)
!7 = !DILocation(line: 210, column: 12, scope: !4)
!8 = !{!9}
!9 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
diff --git a/llvm/test/DebugInfo/X86/debug-loc-frame.ll b/llvm/test/DebugInfo/X86/debug-loc-frame.ll
index 58b1185..f3bcfcb 100644
--- a/llvm/test/DebugInfo/X86/debug-loc-frame.ll
+++ b/llvm/test/DebugInfo/X86/debug-loc-frame.ll
@@ -28,7 +28,14 @@
; CHECK: DW_TAG_variable
; CHECK: DW_AT_location [DW_FORM_sec_offset] ({{.*}}
; CHECK-NEXT: [{{0x.*}}, {{0x.*}}): DW_OP_reg0 RAX
-; CHECK-NEXT: [{{0x.*}}, {{0x.*}}): DW_OP_breg7 RSP+4, DW_OP_deref)
+;
+; Note: This is a location, so we don't want an extra DW_OP_deref at the end.
+; LLDB gets the location right without it:
+; Variable: ... name = "val", type = "int", location = [rsp+4], decl = frame.c:10
+; Adding the deref actually creates an invalid location:
+; ... [rsp+4] DW_OP_deref
+;
+; CHECK-NEXT: [{{0x.*}}, {{0x.*}}): DW_OP_breg7 RSP+4)
; CHECK-NEXT: DW_AT_name {{.*}}"val"
; ModuleID = 'frame.c'