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[CFI/MergeFunctions] Modify MergeFunctions to propagate type information #68628

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Oct 18, 2023
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[CFI/MergeFunctions] Modify MergeFunctions to propagate type information #68628

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13 changes: 13 additions & 0 deletions llvm/lib/Transforms/IPO/MergeFunctions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -662,6 +662,13 @@ static bool canCreateThunkFor(Function *F) {
return true;
}

/// Copy metadata from one function to another.
static void copyMetadataIfPresent(Function *From, Function *To, StringRef Key) {
if (MDNode *MD = From->getMetadata(Key)) {
To->setMetadata(Key, MD);
}
}

// Replace G with a simple tail call to bitcast(F). Also (unless
// MergeFunctionsPDI holds) replace direct uses of G with bitcast(F),
// delete G. Under MergeFunctionsPDI, we use G itself for creating
Expand Down Expand Up @@ -740,6 +747,9 @@ void MergeFunctions::writeThunk(Function *F, Function *G) {
} else {
NewG->copyAttributesFrom(G);
NewG->takeName(G);
// Ensure CFI type metadata is propagated to the new function.
copyMetadataIfPresent(G, NewG, "type");
copyMetadataIfPresent(G, NewG, "kcfi_type");
removeUsers(G);
G->replaceAllUsesWith(NewG);
G->eraseFromParent();
Expand Down Expand Up @@ -815,6 +825,9 @@ void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
F->getAddressSpace(), "", F->getParent());
NewF->copyAttributesFrom(F);
NewF->takeName(F);
// Ensure CFI type metadata is propagated to the new function.
copyMetadataIfPresent(F, NewF, "type");
copyMetadataIfPresent(F, NewF, "kcfi_type");
removeUsers(F);
F->replaceAllUsesWith(NewF);

Expand Down
210 changes: 210 additions & 0 deletions llvm/test/Transforms/MergeFunc/cfi-thunk-merging.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,210 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --include-generated-funcs --version 2
;; Check the cases involving internal CFI instrumented functions where we do not expect functions to be merged.
; RUN: opt -S -passes=mergefunc < %s | FileCheck %s
; RUN: opt -S -passes=mergefunc,lowertypetests < %s | FileCheck --check-prefix=LOWERTYPETESTS %s

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux"

@0 = private unnamed_addr constant { i16, i16, [12 x i8] } { i16 -1, i16 0, [12 x i8] c"'int (int)'\00" }

; Function Attrs: noinline nounwind optnone
define dso_local i32 @f(i32 noundef %arg) #0 !type !3 !type !4 {
entry:
%arg.addr = alloca i32, align 4
%a = alloca i32, align 4
%b = alloca i32, align 4
store i32 %arg, ptr %arg.addr, align 4
store i32 0, ptr %b, align 4
%0 = load i32, ptr %arg.addr, align 4
%cmp = icmp sgt i32 %0, 0
br i1 %cmp, label %if.then, label %if.end

if.then: ; preds = %entry
store i32 1, ptr %a, align 4
br label %if.end

if.end: ; preds = %if.then, %entry
%1 = load i32, ptr %a, align 4
%2 = load i32, ptr %b, align 4
%add = add nsw i32 %1, %2
ret i32 %add
}

; Function Attrs: noinline nounwind optnone
define dso_local i32 @f_thunk(i32 noundef %arg) #0 !type !3 !type !4 {
entry:
%arg.addr = alloca i32, align 4
%a = alloca i32, align 4
%b = alloca i32, align 4
store i32 %arg, ptr %arg.addr, align 4
store i32 0, ptr %b, align 4
%0 = load i32, ptr %arg.addr, align 4
%cmp = icmp sgt i32 %0, 0
br i1 %cmp, label %if.then, label %if.end

if.then: ; preds = %entry
store i32 1, ptr %a, align 4
br label %if.end

if.end: ; preds = %if.then, %entry
%1 = load i32, ptr %a, align 4
%2 = load i32, ptr %b, align 4
%add = add nsw i32 %1, %2
ret i32 %add
}

; Function Attrs: noinline nounwind optnone
define dso_local i32 @g(i32 noundef %b) #0 !type !3 !type !4 {
entry:
%b.addr = alloca i32, align 4
%fp = alloca ptr, align 8
store i32 %b, ptr %b.addr, align 4
%0 = load i32, ptr %b.addr, align 4
%tobool = icmp ne i32 %0, 0
%1 = zext i1 %tobool to i64
%cond = select i1 %tobool, ptr @f, ptr @f_thunk
store ptr %cond, ptr %fp, align 8
%2 = load ptr, ptr %fp, align 8
%3 = call i1 @llvm.type.test(ptr %2, metadata !"_ZTSFiiE"), !nosanitize !5
br i1 %3, label %cont, label %trap, !nosanitize !5

trap: ; preds = %entry
call void @llvm.ubsantrap(i8 2) #3, !nosanitize !5
unreachable, !nosanitize !5

cont: ; preds = %entry
%4 = load i32, ptr %b.addr, align 4
%call = call i32 %2(i32 noundef %4)
ret i32 %call
}

; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
declare i1 @llvm.type.test(ptr, metadata) #1

; Function Attrs: cold noreturn nounwind
declare void @llvm.ubsantrap(i8 immarg) #2

attributes #0 = { noinline nounwind optnone "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+cx8,+mmx,+sse,+sse2,+x87" }
attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
attributes #2 = { cold noreturn nounwind }
attributes #3 = { noreturn nounwind }

!llvm.module.flags = !{!0, !1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 4, !"CFI Canonical Jump Tables", i32 0}
!3 = !{i64 0, !"_ZTSFiiE"}
!4 = !{i64 0, !"_ZTSFiiE.generalized"}
!5 = !{}
; CHECK-LABEL: define dso_local i32 @f
; CHECK-SAME: (i32 noundef [[ARG:%.*]]) #[[ATTR0:[0-9]+]] !type !2 !type !3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[ARG_ADDR:%.*]] = alloca i32, align 4
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: [[B:%.*]] = alloca i32, align 4
; CHECK-NEXT: store i32 [[ARG]], ptr [[ARG_ADDR]], align 4
; CHECK-NEXT: store i32 0, ptr [[B]], align 4
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[ARG_ADDR]], align 4
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[TMP0]], 0
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: store i32 1, ptr [[A]], align 4
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[A]], align 4
; CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[B]], align 4
; CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[TMP1]], [[TMP2]]
; CHECK-NEXT: ret i32 [[ADD]]
;
;
; CHECK-LABEL: define dso_local i32 @g
; CHECK-SAME: (i32 noundef [[B:%.*]]) #[[ATTR0]] !type !2 !type !3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[B_ADDR:%.*]] = alloca i32, align 4
; CHECK-NEXT: [[FP:%.*]] = alloca ptr, align 8
; CHECK-NEXT: store i32 [[B]], ptr [[B_ADDR]], align 4
; CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[B_ADDR]], align 4
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne i32 [[TMP0]], 0
; CHECK-NEXT: [[TMP1:%.*]] = zext i1 [[TOBOOL]] to i64
; CHECK-NEXT: [[COND:%.*]] = select i1 [[TOBOOL]], ptr @f, ptr @f_thunk
; CHECK-NEXT: store ptr [[COND]], ptr [[FP]], align 8
; CHECK-NEXT: [[TMP2:%.*]] = load ptr, ptr [[FP]], align 8
; CHECK-NEXT: [[TMP3:%.*]] = call i1 @llvm.type.test(ptr [[TMP2]], metadata !"_ZTSFiiE"), !nosanitize !4
; CHECK-NEXT: br i1 [[TMP3]], label [[CONT:%.*]], label [[TRAP:%.*]], !nosanitize !4
; CHECK: trap:
; CHECK-NEXT: call void @llvm.ubsantrap(i8 2) #[[ATTR3:[0-9]+]], !nosanitize !4
; CHECK-NEXT: unreachable, !nosanitize !4
; CHECK: cont:
; CHECK-NEXT: [[TMP4:%.*]] = load i32, ptr [[B_ADDR]], align 4
; CHECK-NEXT: [[CALL:%.*]] = call i32 [[TMP2]](i32 noundef [[TMP4]])
; CHECK-NEXT: ret i32 [[CALL]]
;
;
; CHECK-LABEL: define dso_local i32 @f_thunk
; CHECK-SAME: (i32 noundef [[TMP0:%.*]]) #[[ATTR0]] !type !2 {
; CHECK-NEXT: [[TMP2:%.*]] = tail call i32 @f(i32 noundef [[TMP0]]) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[TMP2]]
;
;
; LOWERTYPETESTS-LABEL: define dso_local i32 @f
; LOWERTYPETESTS-SAME: (i32 noundef [[ARG:%.*]]) #[[ATTR0:[0-9]+]] !type !2 !type !3 {
; LOWERTYPETESTS-NEXT: entry:
; LOWERTYPETESTS-NEXT: [[ARG_ADDR:%.*]] = alloca i32, align 4
; LOWERTYPETESTS-NEXT: [[A:%.*]] = alloca i32, align 4
; LOWERTYPETESTS-NEXT: [[B:%.*]] = alloca i32, align 4
; LOWERTYPETESTS-NEXT: store i32 [[ARG]], ptr [[ARG_ADDR]], align 4
; LOWERTYPETESTS-NEXT: store i32 0, ptr [[B]], align 4
; LOWERTYPETESTS-NEXT: [[TMP0:%.*]] = load i32, ptr [[ARG_ADDR]], align 4
; LOWERTYPETESTS-NEXT: [[CMP:%.*]] = icmp sgt i32 [[TMP0]], 0
; LOWERTYPETESTS-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; LOWERTYPETESTS: if.then:
; LOWERTYPETESTS-NEXT: store i32 1, ptr [[A]], align 4
; LOWERTYPETESTS-NEXT: br label [[IF_END]]
; LOWERTYPETESTS: if.end:
; LOWERTYPETESTS-NEXT: [[TMP1:%.*]] = load i32, ptr [[A]], align 4
; LOWERTYPETESTS-NEXT: [[TMP2:%.*]] = load i32, ptr [[B]], align 4
; LOWERTYPETESTS-NEXT: [[ADD:%.*]] = add nsw i32 [[TMP1]], [[TMP2]]
; LOWERTYPETESTS-NEXT: ret i32 [[ADD]]
;
;
; LOWERTYPETESTS-LABEL: define dso_local i32 @g
; LOWERTYPETESTS-SAME: (i32 noundef [[B:%.*]]) #[[ATTR0]] !type !2 !type !3 {
; LOWERTYPETESTS-NEXT: entry:
; LOWERTYPETESTS-NEXT: [[B_ADDR:%.*]] = alloca i32, align 4
; LOWERTYPETESTS-NEXT: [[FP:%.*]] = alloca ptr, align 8
; LOWERTYPETESTS-NEXT: store i32 [[B]], ptr [[B_ADDR]], align 4
; LOWERTYPETESTS-NEXT: [[TMP0:%.*]] = load i32, ptr [[B_ADDR]], align 4
; LOWERTYPETESTS-NEXT: [[TOBOOL:%.*]] = icmp ne i32 [[TMP0]], 0
; LOWERTYPETESTS-NEXT: [[TMP1:%.*]] = zext i1 [[TOBOOL]] to i64
; LOWERTYPETESTS-NEXT: [[COND:%.*]] = select i1 [[TOBOOL]], ptr @.cfi.jumptable, ptr getelementptr inbounds ([2 x [8 x i8]], ptr @.cfi.jumptable, i64 0, i64 1)
; LOWERTYPETESTS-NEXT: store ptr [[COND]], ptr [[FP]], align 8
; LOWERTYPETESTS-NEXT: [[TMP2:%.*]] = load ptr, ptr [[FP]], align 8
; LOWERTYPETESTS-NEXT: [[TMP3:%.*]] = ptrtoint ptr [[TMP2]] to i64
; LOWERTYPETESTS-NEXT: [[TMP4:%.*]] = sub i64 [[TMP3]], ptrtoint (ptr @.cfi.jumptable to i64)
; LOWERTYPETESTS-NEXT: [[TMP5:%.*]] = lshr i64 [[TMP4]], 3
; LOWERTYPETESTS-NEXT: [[TMP6:%.*]] = shl i64 [[TMP4]], 61
; LOWERTYPETESTS-NEXT: [[TMP7:%.*]] = or i64 [[TMP5]], [[TMP6]]
; LOWERTYPETESTS-NEXT: [[TMP8:%.*]] = icmp ule i64 [[TMP7]], 1
; LOWERTYPETESTS-NEXT: br i1 [[TMP8]], label [[CONT:%.*]], label [[TRAP:%.*]], !nosanitize !4
; LOWERTYPETESTS: trap:
; LOWERTYPETESTS-NEXT: call void @llvm.ubsantrap(i8 2) #[[ATTR4:[0-9]+]], !nosanitize !4
; LOWERTYPETESTS-NEXT: unreachable, !nosanitize !4
; LOWERTYPETESTS: cont:
; LOWERTYPETESTS-NEXT: [[TMP9:%.*]] = load i32, ptr [[B_ADDR]], align 4
; LOWERTYPETESTS-NEXT: [[CALL:%.*]] = call i32 [[TMP2]](i32 noundef [[TMP9]])
; LOWERTYPETESTS-NEXT: ret i32 [[CALL]]
;
;
; LOWERTYPETESTS-LABEL: define dso_local i32 @f_thunk
; LOWERTYPETESTS-SAME: (i32 noundef [[TMP0:%.*]]) #[[ATTR0]] !type !2 {
; LOWERTYPETESTS-NEXT: [[TMP2:%.*]] = tail call i32 @f(i32 noundef [[TMP0]]) #[[ATTR0]]
; LOWERTYPETESTS-NEXT: ret i32 [[TMP2]]
;
;
; LOWERTYPETESTS-LABEL: define private void @.cfi.jumptable
; LOWERTYPETESTS-SAME: () #[[ATTR3:[0-9]+]] align 8 {
; LOWERTYPETESTS-NEXT: entry:
; LOWERTYPETESTS-NEXT: call void asm sideeffect "jmp ${0:c}@plt\0Aint3\0Aint3\0Aint3\0Ajmp ${1:c}@plt\0Aint3\0Aint3\0Aint3\0A", "s,s"(ptr @f, ptr @f_thunk)
; LOWERTYPETESTS-NEXT: unreachable
;