[llvm] 74a72e6 - [DebugInfo] Stop describing imms in TargetInstrInfo's describeLoadedValue() impl
David Stenberg via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 23 02:57:37 PDT 2019
Author: David Stenberg
Date: 2019-10-23T11:41:29+02:00
New Revision: 74a72e684849d00dbe5cc784cf05d20fd8873cdb
URL: https://github.com/llvm/llvm-project/commit/74a72e684849d00dbe5cc784cf05d20fd8873cdb
DIFF: https://github.com/llvm/llvm-project/commit/74a72e684849d00dbe5cc784cf05d20fd8873cdb.diff
LOG: [DebugInfo] Stop describing imms in TargetInstrInfo's describeLoadedValue() impl
Summary:
The default implementation of the describeLoadedValue() hook uses the
MoveImm property to determine if an instruction moves an immediate. If
an instruction has that property the function returns the second
operand, assuming that that is the immediate value the instruction
moves. As far as I can tell, the MoveImm property does not imply that
the second operand is the immediate value, nor that any other operand
necessarily holds the immediate value; it just means that the
instruction moves some immediate value.
One example where the second operand is not the immediate is SystemZ's
LZER instruction, which moves a zero immediate implicitly: $f0S = LZER.
That case triggered an out-of-bound assertion when getting the operand.
I have added a test case for that instruction.
Another example is ARM's MVN instruction, which holds the logical
bitwise NOT'd value of the immediate that is moved. For the following
reproducer:
extern void foo(int);
int main() { foo(-11); }
an incorrect call site value would be emitted:
$ clang --target=arm foo.c -O1 -g -Xclang -femit-debug-entry-values \
-c -o - | ./build/bin/llvm-dwarfdump - | \
grep -A2 call_site_parameter
0x00000058: DW_TAG_GNU_call_site_parameter
DW_AT_location (DW_OP_reg0 R0)
DW_AT_GNU_call_site_value (DW_OP_lit10)
Another example is the A2_combineii instruction on Hexagon which moves
two immediates to a super-register: $d0 = A2_combineii 20, 10.
Perhaps these are rare exceptions, and most MoveImm instructions hold
the immediate in the second operand, but in my opinion the default
implementation of the hook should only describe values that it can, by
some contract, guarantee are safe to describe, rather than leaving it up
to the targets to override the exceptions, as that can silently result
in incorrect call site values.
This patch adds X86's relevant move immediate instructions to the
target's hook implementation, so this commit should be a NFC for that
target. We need to do the same for ARM and AArch64.
Reviewers: djtodoro, NikolaPrica, aprantl, vsk
Reviewed By: vsk
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #debug-info, #llvm
Differential Revision: https://reviews.llvm.org/D69109
Added:
llvm/test/DebugInfo/MIR/SystemZ/call-site-lzer.mir
llvm/test/DebugInfo/MIR/SystemZ/lit.local.cfg
Modified:
llvm/lib/CodeGen/TargetInstrInfo.cpp
llvm/lib/Target/X86/X86InstrInfo.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 6cae3b869501..d99b2b0e9977 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1130,9 +1130,6 @@ TargetInstrInfo::describeLoadedValue(const MachineInstr &MI) const {
if (isCopyInstr(MI, SrcRegOp, DestRegOp)) {
Op = SrcRegOp;
return ParamLoadedValue(*Op, Expr);
- } else if (MI.isMoveImmediate()) {
- Op = &MI.getOperand(1);
- return ParamLoadedValue(*Op, Expr);
}
return None;
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index c29029daeec9..889ba288cc20 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -7638,12 +7638,17 @@ X86InstrInfo::describeLoadedValue(const MachineInstr &MI) const {
return ParamLoadedValue(*Op, Expr);;
}
+ case X86::MOV32ri:
+ case X86::MOV64ri:
+ case X86::MOV64ri32:
+ return ParamLoadedValue(MI.getOperand(1), Expr);
case X86::XOR32rr: {
if (MI.getOperand(1).getReg() == MI.getOperand(2).getReg())
return ParamLoadedValue(MachineOperand::CreateImm(0), Expr);
return None;
}
default:
+ assert(!MI.isMoveImmediate() && "Unexpected MoveImm instruction");
return TargetInstrInfo::describeLoadedValue(MI);
}
}
diff --git a/llvm/test/DebugInfo/MIR/SystemZ/call-site-lzer.mir b/llvm/test/DebugInfo/MIR/SystemZ/call-site-lzer.mir
new file mode 100644
index 000000000000..8a4e8b5632c2
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/SystemZ/call-site-lzer.mir
@@ -0,0 +1,83 @@
+# RUN: llc -debug-entry-values -start-after=livedebugvalues -o - %s | FileCheck %s
+
+# This test would previously trigger an assertion when trying to describe the
+# call site value for callee()'s float parameter.
+#
+# Please note that at the time of creating this test the SystemZ target did not
+# support call site information, so the "callSites" array has been manually
+# added. For now, verify that we don't crash, and that no (invalid) call site
+# parameter entry is emitted, but later on when call site information is added
+# to the target the LZER instruction should be properly described.
+
+# CHECK-NOT: DW_TAG_GNU_call_site_parameter
+
+# Based on the following C reproducer:
+#
+# extern void callee(float);
+# int caller() {
+# callee(0);
+# return 0;
+# }
+
+--- |
+ target datalayout = "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-a:8:16-n32:64"
+ target triple = "systemz"
+
+ ; Function Attrs: nounwind
+ define signext i32 @caller() !dbg !12 {
+ entry:
+ tail call void @callee(float 0.000000e+00), !dbg !16
+ ret i32 0, !dbg !17
+ }
+
+ declare !dbg !4 void @callee(float)
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!8, !9, !10}
+ !llvm.ident = !{!11}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+ !1 = !DIFile(filename: "systemz-lzer.c", directory: "/")
+ !2 = !{}
+ !3 = !{!4}
+ !4 = !DISubprogram(name: "callee", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+ !5 = !DISubroutineType(types: !6)
+ !6 = !{null, !7}
+ !7 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+ !8 = !{i32 2, !"Dwarf Version", i32 4}
+ !9 = !{i32 2, !"Debug Info Version", i32 3}
+ !10 = !{i32 1, !"wchar_size", i32 4}
+ !11 = !{!"clang version 10.0.0"}
+ !12 = distinct !DISubprogram(name: "caller", scope: !1, file: !1, line: 2, type: !13, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+ !13 = !DISubroutineType(types: !14)
+ !14 = !{!15}
+ !15 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !16 = !DILocation(line: 3, scope: !12)
+ !17 = !DILocation(line: 4, scope: !12)
+
+...
+---
+name: caller
+tracksRegLiveness: true
+callSites:
+ - { bb: 0, offset: 9, fwdArgRegs:
+ - { arg: 0, reg: '$f0s' } }
+body: |
+ bb.0.entry:
+ liveins: $r11d, $r15d, $r14d
+
+ STMG killed $r11d, killed $r15d, $r15d, 88, implicit killed $r14d
+ CFI_INSTRUCTION offset $r11d, -72
+ CFI_INSTRUCTION offset $r14d, -48
+ CFI_INSTRUCTION offset $r15d, -40
+ $r15d = AGHI $r15d, -160, implicit-def dead $cc
+ CFI_INSTRUCTION def_cfa_offset 320
+ $r11d = LGR $r15d
+ CFI_INSTRUCTION def_cfa_register $r11d
+ renamable $f0s = LZER
+ CallBRASL @callee, $f0s, csr_systemz, implicit-def dead $r14d, implicit-def dead $cc, implicit $fpc, debug-location !16
+ $r2d = LGHI 0, debug-location !17
+ $r11d, $r15d = LMG $r11d, 248, implicit-def $r14d, debug-location !17
+ Return implicit killed $r2d, debug-location !17
+
+...
diff --git a/llvm/test/DebugInfo/MIR/SystemZ/lit.local.cfg b/llvm/test/DebugInfo/MIR/SystemZ/lit.local.cfg
new file mode 100644
index 000000000000..2f3cf7d3f043
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/SystemZ/lit.local.cfg
@@ -0,0 +1,2 @@
+if not 'SystemZ' in config.root.targets:
+ config.unsupported = True
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