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[FuncSpec] Don't specialise (or crash) on poison or constexpr values 

Function specialization was crashing on poison values and constexpr values.
The problem is that these values are not added to the solver, so it crashes
when a lookup is performed for these values. This fixes that by not
specialising on these values. For poison that is obvious, but for constexpr
this is a change in behaviour. Thus, in one way this is a bit of a stopgap, but
specialising on constexpr values wasn't done very intentionally, and need some
more work and tests if we wanted to support this.

As a follow up, we need to look if the solver should exit more gracefully and
return a "don't know", or that it should really support these constexprs.

This should fix PR51600 (https://bugs.llvm.org/show_bug.cgi?id=51600).

Differential Revision: https://reviews.llvm.org/D110529
This commit is contained in:
Sjoerd Meijer 2021-09-27 08:39:53 +01:00
parent ebee606e38
commit eba76056a3
4 changed files with 124 additions and 42 deletions
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5
llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
View File

@ -675,6 +675,11 @@ private:
continue;
auto *V = CS.getArgOperand(A->getArgNo());
if (isa<PoisonValue>(V))
return false;
if (isa<ConstantExpr>(V))
return false;
// TrackValueOfGlobalVariable only tracks scalar global variables.
if (auto *GV = dyn_cast<GlobalVariable>(V)) {
// Check if we want to specialize on the address of non-constant

75
llvm/test/Transforms/FunctionSpecialization/function-specialization-constant-expression.ll
View File

@ -9,38 +9,6 @@
%struct = type { i8, i16, i32, i64, i64}
@Global = internal constant %struct {i8 0, i16 1, i32 2, i64 3, i64 4}
define internal i64 @zoo(i1 %flag) {
; CHECK-LABEL: @zoo(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[FLAG:%.*]], label [[PLUS:%.*]], label [[MINUS:%.*]]
; CHECK: plus:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @func2.1(i64* getelementptr inbounds ([[STRUCT:%.*]], %struct* @Global, i32 0, i32 3))
; CHECK-NEXT: br label [[MERGE:%.*]]
; CHECK: minus:
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @func2.2(i64* getelementptr inbounds ([[STRUCT]], %struct* @Global, i32 0, i32 4))
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: [[TMP2:%.*]] = phi i64 [ [[TMP0]], [[PLUS]] ], [ [[TMP1]], [[MINUS]] ]
; CHECK-NEXT: ret i64 [[TMP2]]
;
entry:
br i1 %flag, label %plus, label %minus
plus:
%arg = getelementptr %struct, %struct* @Global, i32 0, i32 3
%tmp0 = call i64 @func2(i64* %arg)
br label %merge
minus:
%arg2 = getelementptr %struct, %struct* @Global, i32 0, i32 4
%tmp1 = call i64 @func2(i64* %arg2)
br label %merge
merge:
%tmp2 = phi i64 [ %tmp0, %plus ], [ %tmp1, %minus]
ret i64 %tmp2
}
define internal i64 @func2(i64 *%x) {
; CHECK-LABEL: @func2(
; CHECK-NEXT: entry:
@ -63,6 +31,39 @@ entry:
ret i64 %tmp0
}
define internal i64 @zoo(i1 %flag) {
; CHECK-LABEL: @zoo(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[FLAG:%.*]], label [[PLUS:%.*]], label [[MINUS:%.*]]
; CHECK: plus:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @func2(i64* getelementptr inbounds ([[STRUCT:%.*]], %struct* @Global, i32 0, i32 3))
; CHECK-NEXT: br label [[MERGE:%.*]]
; CHECK: minus:
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @func2(i64* getelementptr inbounds ([[STRUCT]], %struct* @Global, i32 0, i32 4))
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: [[TMP2:%.*]] = phi i64 [ [[TMP0]], [[PLUS]] ], [ [[TMP1]], [[MINUS]] ]
; CHECK-NEXT: ret i64 [[TMP2]]
;
entry:
br i1 %flag, label %plus, label %minus
plus:
%arg = getelementptr %struct, %struct* @Global, i32 0, i32 3
%tmp0 = call i64 @func2(i64* %arg)
br label %merge
minus:
%arg2 = getelementptr %struct, %struct* @Global, i32 0, i32 4
%tmp1 = call i64 @func2(i64* %arg2)
br label %merge
merge:
%tmp2 = phi i64 [ %tmp0, %plus ], [ %tmp1, %minus]
ret i64 %tmp2
}
define i64 @main() {
; CHECK-LABEL: @main(
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @zoo(i1 false)
@ -75,13 +76,3 @@ define i64 @main() {
%3 = add i64 %1, %2
ret i64 %3
}
; CHECK-LABEL: define internal i64 @func2.1(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret i64 ptrtoint (i64* getelementptr inbounds (%struct, %struct* @Global, i32 0, i32 3) to i64)
; CHECK-NEXT: }
; CHECK-LABEL: define internal i64 @func2.2(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret i64 ptrtoint (i64* getelementptr inbounds (%struct, %struct* @Global, i32 0, i32 4) to i64)
; CHECK-NEXT: }

44
llvm/test/Transforms/FunctionSpecialization/function-specialization-constant-expression2.ll Normal file
View File

@ -0,0 +1,44 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -function-specialization -force-function-specialization -S < %s | FileCheck %s
; Check that we don't crash and specialise on a constant expression.
%struct.pluto = type { %struct.spam }
%struct.quux = type { i16 }
%struct.spam = type { i16 }
@global.5 = external dso_local global [4 x %struct.pluto], align 1
@global.12 = external global %struct.quux, align 1
define internal i16 @wobble.972(%struct.quux* byval(%struct.quux) align 1 %arg, i16 %arg1, %struct.spam* byval(%struct.spam) align 1 %arg2, %struct.quux* byval(%struct.quux) align 1 %arg3) #4 {
; CHECK-LABEL: @wobble.972(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[TMP34:%.*]] = bitcast %struct.spam* [[ARG2:%.*]] to i16*
; CHECK-NEXT: unreachable
;
bb:
%tmp34 = bitcast %struct.spam* %arg2 to i16*
unreachable
}
define internal i16 @snork() {
; CHECK-LABEL: @snork(
; CHECK-NEXT: bb4:
; CHECK-NEXT: [[TMP:%.*]] = call i16 @wobble.972(%struct.quux* byval([[STRUCT_QUUX:%.*]]) align 1 undef, i16 undef, %struct.spam* byval([[STRUCT_SPAM:%.*]]) align 1 getelementptr inbounds ([4 x %struct.pluto], [4 x %struct.pluto]* @global.5, i32 0, i32 3, i32 0), %struct.quux* byval([[STRUCT_QUUX]]) align 1 @global.12)
; CHECK-NEXT: unreachable
;
bb4:
%tmp = call i16 @wobble.972(%struct.quux* byval(%struct.quux) align 1 undef, i16 undef, %struct.spam* byval(%struct.spam) align 1 getelementptr inbounds ([4 x %struct.pluto], [4 x %struct.pluto]* @global.5, i32 0, i32 3, i32 0), %struct.quux* byval(%struct.quux) align 1 @global.12)
unreachable
}
define i16 @main() {
; CHECK-LABEL: @main(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[TMP:%.*]] = call i16 @snork()
; CHECK-NEXT: unreachable
;
bb:
%tmp = call i16 @snork()
unreachable
}

42
llvm/test/Transforms/FunctionSpecialization/function-specialization-poison.ll Normal file
View File

@ -0,0 +1,42 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -function-specialization -force-function-specialization -S < %s | FileCheck %s
; Check that we don't crash and specialise on a poison value.
%struct.quux = type { i16 }
%struct.spam = type { i16 }
@global.12 = external global %struct.quux, align 1
define internal i16 @wobble(%struct.spam* byval(%struct.spam) %arg2) {
; CHECK-LABEL: @wobble(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[C:%.*]] = bitcast %struct.spam* [[ARG2:%.*]] to i16*
; CHECK-NEXT: unreachable
;
bb:
%C = bitcast %struct.spam* %arg2 to i16*
unreachable
}
define internal i16 @snork() {
; CHECK-LABEL: @snork(
; CHECK-NEXT: bb4:
; CHECK-NEXT: [[B:%.*]] = call i16 @wobble(%struct.spam* poison)
; CHECK-NEXT: unreachable
;
bb4:
%B = call i16 @wobble(%struct.spam* poison)
unreachable
}
define i16 @main() {
; CHECK-LABEL: @main(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[A:%.*]] = call i16 @snork()
; CHECK-NEXT: unreachable
;
bb:
%A = call i16 @snork()
unreachable
}