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[DebugInfo] Handle DIArgList in FastISel or GlobalIsel 

Currently, variadic dbg.values (i.e. those using a DIArgList as part of
their location) are not handled properly by FastISel or GlobalISel, and
will produce invalid DBG_VALUE instructions if they encounter them. This
patch fixes this issue by emitting undef DBG_VALUE instructions for
variadic dbg.values, so that no incorrect instruction is produced and
any prior variable location is terminated.

This is simply a quick-fix to prevent errors; a correct implementation
should come later for these ISel pipelines to ensure that we do not drop
debug information unnecessarily.

Differential Revision: https://reviews.llvm.org/D102500
This commit is contained in:
Stephen Tozer 2021-05-20 16:33:38 +01:00
parent 943839870a
commit cf725dde9c
3 changed files with 19 additions and 11 deletions
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6
llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
View File

@ -1925,9 +1925,9 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
assert(DI.getVariable()->isValidLocationForIntrinsic(
MIRBuilder.getDebugLoc()) &&
"Expected inlined-at fields to agree");
if (!V) {
// Currently the optimizer can produce this; insert an undef to
// help debugging. Probably the optimizer should not do this.
if (!V || DI.hasArgList()) {
// DI cannot produce a valid DBG_VALUE, so produce an undef DBG_VALUE to
// terminate any prior location.
MIRBuilder.buildIndirectDbgValue(0, DI.getVariable(), DI.getExpression());
} else if (const auto *CI = dyn_cast<Constant>(V)) {
MIRBuilder.buildConstDbgValue(*CI, DI.getVariable(), DI.getExpression());

6
llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
View File

@ -1277,9 +1277,9 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
const Value *V = DI->getValue();
assert(DI->getVariable()->isValidLocationForIntrinsic(DbgLoc) &&
"Expected inlined-at fields to agree");
if (!V || isa<UndefValue>(V)) {
// Currently the optimizer can produce this; insert an undef to
// help debugging.
if (!V || isa<UndefValue>(V) || DI->hasArgList()) {
// DI is either undef or cannot produce a valid DBG_VALUE, so produce an
// undef DBG_VALUE to terminate any prior location.
BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, false, 0U,
DI->getVariable(), DI->getExpression());
} else if (const auto *CI = dyn_cast<ConstantInt>(V)) {

18
llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll
View File

@ -1,4 +1,6 @@
; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck %s
; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,DAG %s
; RUN: llc %s -fast-isel=true -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,FAST %s
; RUN: llc %s -global-isel=true -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,GLOBAL %s
;; Test that a dbg.value that uses a DIArgList is correctly converted to a
;; DBG_VALUE_LIST that uses the registers corresponding to its operands.
@ -6,10 +8,16 @@
; CHECK-DAG: [[A_VAR:![0-9]+]] = !DILocalVariable(name: "a"
; CHECK-DAG: [[B_VAR:![0-9]+]] = !DILocalVariable(name: "b"
; CHECK-DAG: [[C_VAR:![0-9]+]] = !DILocalVariable(name: "c"
; CHECK-LABEL: bb.0.entry
; CHECK-DAG: DBG_VALUE_LIST [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %0, debug-location
; CHECK-DAG: DBG_VALUE_LIST [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %1, debug-location
; CHECK: DBG_VALUE_LIST [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), %0, %1, debug-location
; CHECK-LABEL: bb.{{(0|1)}}.entry
; DAG-DAG: DBG_VALUE_LIST [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %0, debug-location
; DAG-DAG: DBG_VALUE_LIST [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %1, debug-location
; DAG: DBG_VALUE_LIST [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), %0, %1, debug-location
; FAST-DAG: DBG_VALUE $noreg, $noreg, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
; FAST-DAG: DBG_VALUE $noreg, $noreg, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
; FAST: DBG_VALUE $noreg, $noreg, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
; GLOBAL: DBG_VALUE $noreg, 0, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc19.16.27034"