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[InstCombine] Don't change fn signature for calls to declarations #102596

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Aug 12, 2024
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[InstCombine] Don't change fn signature for calls to declarations #102596

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28 changes: 6 additions & 22 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4106,6 +4106,12 @@ bool InstCombinerImpl::transformConstExprCastCall(CallBase &Call) {
assert(!isa<CallBrInst>(Call) &&
"CallBr's don't have a single point after a def to insert at");

// Don't perform the transform for declarations, which may not be fully
// accurate. For example, void @foo() is commonly used as a placeholder for
// unknown prototypes.
if (Callee->isDeclaration())
return false;

// If this is a call to a thunk function, don't remove the cast. Thunks are
// used to transparently forward all incoming parameters and outgoing return
// values, so it's important to leave the cast in place.
Expand Down Expand Up @@ -4142,9 +4148,6 @@ bool InstCombinerImpl::transformConstExprCastCall(CallBase &Call) {
return false; // TODO: Handle multiple return values.

if (!CastInst::isBitOrNoopPointerCastable(NewRetTy, OldRetTy, DL)) {
if (Callee->isDeclaration())
return false; // Cannot transform this return value.

if (!Caller->use_empty())
return false; // Cannot transform this return value.
}
Expand Down Expand Up @@ -4212,25 +4215,6 @@ bool InstCombinerImpl::transformConstExprCastCall(CallBase &Call) {
return false; // Cannot transform to or from byval.
}

if (Callee->isDeclaration()) {
// Do not delete arguments unless we have a function body.
if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
return false;

// If the callee is just a declaration, don't change the varargsness of the
// call. We don't want to introduce a varargs call where one doesn't
// already exist.
if (FT->isVarArg() != Call.getFunctionType()->isVarArg())
return false;

// If both the callee and the cast type are varargs, we still have to make
// sure the number of fixed parameters are the same or we have the same
// ABI issues as if we introduce a varargs call.
if (FT->isVarArg() && Call.getFunctionType()->isVarArg() &&
FT->getNumParams() != Call.getFunctionType()->getNumParams())
return false;
}

if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
!CallerPAL.isEmpty()) {
// In this case we have more arguments than the new function type, but we
Expand Down
15 changes: 13 additions & 2 deletions llvm/test/Transforms/InstCombine/apint-call-cast-target.ll
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Expand Up @@ -4,8 +4,19 @@
target datalayout = "e-p:32:32"
target triple = "i686-pc-linux-gnu"

declare i32 @main2()
declare ptr @ctime2(ptr)
define i32 @main2() {
; CHECK-LABEL: @main2(
; CHECK-NEXT: ret i32 0
;
ret i32 0
}

define ptr @ctime2(ptr %p) {
; CHECK-LABEL: @ctime2(
; CHECK-NEXT: ret ptr [[P:%.*]]
;
ret ptr %p
}

define ptr @ctime(ptr) {
; CHECK-LABEL: @ctime(
Expand Down
24 changes: 21 additions & 3 deletions llvm/test/Transforms/InstCombine/call-cast-target.ll
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Expand Up @@ -16,7 +16,13 @@ entry:
ret i32 %tmp
}

declare ptr @ctime(ptr)
define ptr @ctime(ptr %p) {
; CHECK-LABEL: define ptr @ctime(
; CHECK-SAME: ptr [[P:%.*]]) {
; CHECK-NEXT: ret ptr [[P]]
;
ret ptr %p
}

define internal { i8 } @foo(ptr) {
; CHECK-LABEL: define internal { i8 } @foo(
Expand All @@ -39,7 +45,13 @@ entry:
ret void
}

declare i32 @fn1(i32)
define i32 @fn1(i32 %x) {
; CHECK-LABEL: define i32 @fn1(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT: ret i32 [[X]]
;
ret i32 %x
}

define i32 @test1(ptr %a) {
; CHECK-LABEL: define i32 @test1(
Expand Down Expand Up @@ -116,7 +128,13 @@ define i1 @test5() {
ret i1 %6
}

declare void @bundles_callee(i32)
define void @bundles_callee(i32) {
; CHECK-LABEL: define void @bundles_callee(
; CHECK-SAME: i32 [[TMP0:%.*]]) {
; CHECK-NEXT: ret void
;
ret void
}

define void @bundles() {
; CHECK-LABEL: define void @bundles() {
Expand Down
6 changes: 3 additions & 3 deletions llvm/test/Transforms/InstCombine/call.ll
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Expand Up @@ -110,7 +110,7 @@ declare i32 @test6a(i32)

define i32 @test6() {
; CHECK-LABEL: define i32 @test6() {
; CHECK-NEXT: [[X:%.*]] = call i32 @test6a(i32 0)
; CHECK-NEXT: [[X:%.*]] = call i32 @test6a()
; CHECK-NEXT: ret i32 [[X]]
;
%X = call i32 @test6a( )
Expand Down Expand Up @@ -141,12 +141,12 @@ declare void @test8a()
define ptr @test8() personality ptr @__gxx_personality_v0 {
; CHECK-LABEL: define ptr @test8() personality ptr @__gxx_personality_v0 {
; CHECK-NEXT: invoke void @test8a()
; CHECK-NEXT: to label [[INVOKE_CONT:%.*]] unwind label [[TRY_HANDLER:%.*]]
; CHECK-NEXT: to label [[INVOKE_CONT:%.*]] unwind label [[TRY_HANDLER:%.*]]
; CHECK: invoke.cont:
; CHECK-NEXT: unreachable
; CHECK: try.handler:
; CHECK-NEXT: [[EXN:%.*]] = landingpad { ptr, i32 }
; CHECK-NEXT: cleanup
; CHECK-NEXT: cleanup
; CHECK-NEXT: ret ptr null
;
; Don't turn this into "unreachable": the callee and caller don't agree in
Expand Down
10 changes: 4 additions & 6 deletions llvm/test/Transforms/InstCombine/opaque-ptr.ll
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Expand Up @@ -743,8 +743,7 @@ declare void @call_byval(i64, ptr byval(i64))

define void @call_cast_ptr_to_int(ptr %p) {
; CHECK-LABEL: @call_cast_ptr_to_int(
; CHECK-NEXT: [[TMP1:%.*]] = ptrtoint ptr [[P:%.*]] to i64
; CHECK-NEXT: call void @call_i64(i64 [[TMP1]])
; CHECK-NEXT: call void @call_i64(ptr [[P:%.*]])
; CHECK-NEXT: ret void
;
call void @call_i64(ptr %p)
Expand All @@ -753,8 +752,7 @@ define void @call_cast_ptr_to_int(ptr %p) {

define void @call_cast_byval(ptr %p, ptr %p2) {
; CHECK-LABEL: @call_cast_byval(
; CHECK-NEXT: [[TMP1:%.*]] = ptrtoint ptr [[P:%.*]] to i64
; CHECK-NEXT: call void @call_byval(i64 [[TMP1]], ptr byval(double) [[P2:%.*]])
; CHECK-NEXT: call void @call_byval(ptr [[P:%.*]], ptr byval(double) [[P2:%.*]])
; CHECK-NEXT: ret void
;
call void @call_byval(ptr %p, ptr byval(double) %p2)
Expand All @@ -765,8 +763,8 @@ declare float @fmodf(float, float)

define i32 @const_fold_call_with_func_type_mismatch() {
; CHECK-LABEL: @const_fold_call_with_func_type_mismatch(
; CHECK-NEXT: [[V:%.*]] = call float @fmodf(float 0x40091EB860000000, float 2.000000e+00)
; CHECK-NEXT: ret i32 1066527622
; CHECK-NEXT: [[V:%.*]] = call i32 @fmodf(float 0x40091EB860000000, float 2.000000e+00)
; CHECK-NEXT: ret i32 [[V]]
;
%v = call i32 @fmodf(float 0x40091EB860000000, float 2.000000e+00)
ret i32 %v
Expand Down
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