[llvm] r367339 - [WebAssembly] Do not emit tail calls with return type mismatch
Thomas Lively via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 30 11:08:39 PDT 2019
Author: tlively
Date: Tue Jul 30 11:08:39 2019
New Revision: 367339
URL: http://llvm.org/viewvc/llvm-project?rev=367339&view=rev
Log:
[WebAssembly] Do not emit tail calls with return type mismatch
Summary:
return_call and return_call_indirect are only valid if the return
types of the callee and caller match. We were previously not enforcing
that, which was producing invalid modules.
Reviewers: aheejin
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65246
Modified:
llvm/trunk/docs/CodeGenerator.rst
llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
llvm/trunk/test/CodeGen/WebAssembly/tailcall.ll
Modified: llvm/trunk/docs/CodeGenerator.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/CodeGenerator.rst?rev=367339&r1=367338&r2=367339&view=diff
==============================================================================
--- llvm/trunk/docs/CodeGenerator.rst (original)
+++ llvm/trunk/docs/CodeGenerator.rst Tue Jul 30 11:08:39 2019
@@ -2090,9 +2090,14 @@ PowerPC constraints:
* On ppc32/64 GOT/PIC only module-local calls (visibility = hidden or protected)
are supported.
-On WebAssembly, tail calls are lowered to ``return_call`` and
-``return_call_indirect`` instructions whenever the 'tail-call' target attribute
-is enabled.
+WebAssembly constraints:
+
+* No variable argument lists are used
+
+* The 'tail-call' target attribute is enabled.
+
+* The caller and callee's return types must match. The caller cannot
+ be void unless the callee is, too.
Example:
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp?rev=367339&r1=367338&r2=367339&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp Tue Jul 30 11:08:39 2019
@@ -644,13 +644,36 @@ WebAssemblyTargetLowering::LowerCall(Cal
if (CLI.IsPatchPoint)
fail(DL, DAG, "WebAssembly doesn't support patch point yet");
- // Fail if tail calls are required but not enabled
- if (!Subtarget->hasTailCall()) {
- if ((CallConv == CallingConv::Fast && CLI.IsTailCall &&
- MF.getTarget().Options.GuaranteedTailCallOpt) ||
- (CLI.CS && CLI.CS.isMustTailCall()))
- fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
- CLI.IsTailCall = false;
+ if (CLI.IsTailCall) {
+ bool MustTail = CLI.CS && CLI.CS.isMustTailCall();
+ if (Subtarget->hasTailCall() && !CLI.IsVarArg) {
+ // Do not tail call unless caller and callee return types match
+ const Function &F = MF.getFunction();
+ const TargetMachine &TM = getTargetMachine();
+ Type *RetTy = F.getReturnType();
+ SmallVector<MVT, 4> CallerRetTys;
+ SmallVector<MVT, 4> CalleeRetTys;
+ computeLegalValueVTs(F, TM, RetTy, CallerRetTys);
+ computeLegalValueVTs(F, TM, CLI.RetTy, CalleeRetTys);
+ bool TypesMatch = CallerRetTys.size() == CalleeRetTys.size() &&
+ std::equal(CallerRetTys.begin(), CallerRetTys.end(),
+ CalleeRetTys.begin());
+ if (!TypesMatch) {
+ // musttail in this case would be an LLVM IR validation failure
+ assert(!MustTail);
+ CLI.IsTailCall = false;
+ }
+ } else {
+ CLI.IsTailCall = false;
+ if (MustTail) {
+ if (CLI.IsVarArg) {
+ // The return would pop the argument buffer
+ fail(DL, DAG, "WebAssembly does not support varargs tail calls");
+ } else {
+ fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
+ }
+ }
+ }
}
SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp?rev=367339&r1=367338&r2=367339&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp Tue Jul 30 11:08:39 2019
@@ -226,6 +226,17 @@ void WebAssemblyMCInstLower::lower(const
if (WebAssembly::isCallIndirect(MI->getOpcode()))
Params.pop_back();
+ // return_call_indirect instructions have the return type of the
+ // caller
+ if (MI->getOpcode() == WebAssembly::RET_CALL_INDIRECT) {
+ const Function &F = MI->getMF()->getFunction();
+ const TargetMachine &TM = MI->getMF()->getTarget();
+ Type *RetTy = F.getReturnType();
+ SmallVector<MVT, 4> CallerRetTys;
+ computeLegalValueVTs(F, TM, RetTy, CallerRetTys);
+ valTypesFromMVTs(CallerRetTys, Returns);
+ }
+
auto *WasmSym = cast<MCSymbolWasm>(Sym);
auto Signature = make_unique<wasm::WasmSignature>(std::move(Returns),
std::move(Params));
Modified: llvm/trunk/test/CodeGen/WebAssembly/tailcall.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/tailcall.ll?rev=367339&r1=367338&r2=367339&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/tailcall.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/tailcall.ll Tue Jul 30 11:08:39 2019
@@ -1,7 +1,8 @@
; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mattr=+tail-call | FileCheck --check-prefixes=CHECK,SLOW %s
; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -fast-isel -mattr=+tail-call | FileCheck --check-prefixes=CHECK,FAST %s
+; RUN: llc < %s --filetype=obj -mattr=+tail-call | obj2yaml | FileCheck --check-prefix=YAML %s
-; Test that the tail-call attribute is accepted
+; Test that the tail calls lower correctly
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"
@@ -124,6 +125,44 @@ define i32 @mismatched_prototypes() {
ret i32 %v
}
+; CHECK-LABEL: mismatched_return_void:
+; CHECK: i32.call $drop=, baz, $pop{{[0-9]+}}, $pop{{[0-9]+}}, $pop{{[0-9]+}}{{$}}
+; CHECK: return{{$}}
+define void @mismatched_return_void() {
+ %v = tail call i32 @baz(i32 0, i32 42, i32 6)
+ ret void
+}
+
+; CHECK-LABEL: mismatched_return_f32:
+; CHECK: i32.call $push[[L:[0-9]+]]=, baz, $pop{{[0-9]+}}, $pop{{[0-9]+}}, $pop{{[0-9]+}}{{$}}
+; CHECK: f32.reinterpret_i32 $push[[L1:[0-9]+]]=, $pop[[L]]{{$}}
+; CHECK: return $pop[[L1]]{{$}}
+define float @mismatched_return_f32() {
+ %v = tail call i32 @baz(i32 0, i32 42, i32 6)
+ %u = bitcast i32 %v to float
+ ret float %u
+}
+
+; CHECK-LABEL: mismatched_indirect_void:
+; CHECK: i32.call_indirect $drop=, $0, $1, $2, $0{{$}}
+; CHECK: return{{$}}
+define void @mismatched_indirect_void(%fn %f, i32 %x, i32 %y) {
+ %p = extractvalue %fn %f, 0
+ %v = tail call i32 %p(%fn %f, i32 %x, i32 %y)
+ ret void
+}
+
+; CHECK-LABEL: mismatched_indirect_f32:
+; CHECK: i32.call_indirect $push[[L:[0-9]+]]=, $0, $1, $2, $0{{$}}
+; CHECK: f32.reinterpret_i32 $push[[L1:[0-9]+]]=, $pop[[L]]{{$}}
+; CHECK: return $pop[[L1]]{{$}}
+define float @mismatched_indirect_f32(%fn %f, i32 %x, i32 %y) {
+ %p = extractvalue %fn %f, 0
+ %v = tail call i32 %p(%fn %f, i32 %x, i32 %y)
+ %u = bitcast i32 %v to float
+ ret float %u
+}
+
; CHECK-LABEL: mismatched_byval:
; CHECK: i32.store
; CHECK: return_call quux, $pop{{[0-9]+}}{{$}}
@@ -135,13 +174,59 @@ define i32 @mismatched_byval(i32* %x) {
; CHECK-LABEL: varargs:
; CHECK: i32.store
-; CHECK: return_call var, $1{{$}}
+; CHECK: i32.call $0=, var, $1{{$}}
+; CHECK: return $0{{$}}
declare i32 @var(...)
define i32 @varargs(i32 %x) {
%v = tail call i32 (...) @var(i32 %x)
ret i32 %v
}
+; Type transformations inhibit tail calls, even when they are nops
+
+; CHECK-LABEL: mismatched_return_zext:
+; CHECK: i32.call
+define i32 @mismatched_return_zext() {
+ %v = tail call i1 @foo(i1 1)
+ %u = zext i1 %v to i32
+ ret i32 %u
+}
+
+; CHECK-LABEL: mismatched_return_sext:
+; CHECK: i32.call
+define i32 @mismatched_return_sext() {
+ %v = tail call i1 @foo(i1 1)
+ %u = sext i1 %v to i32
+ ret i32 %u
+}
+
+; CHECK-LABEL: mismatched_return_trunc:
+; CHECK: i32.call
+declare i32 @int()
+define i1 @mismatched_return_trunc() {
+ %v = tail call i32 @int()
+ %u = trunc i32 %v to i1
+ ret i1 %u
+}
+
+
+
+; Check that the signatures generated for external indirectly
+; return-called functions include the proper return types
+
+; YAML-LABEL: - Index: 8
+; YAML-NEXT: ReturnType: I32
+; YAML-NEXT: ParamTypes:
+; YAML-NEXT: - I32
+; YAML-NEXT: - F32
+; YAML-NEXT: - I64
+; YAML-NEXT: - F64
+define i32 @unique_caller(i32 (i32, float, i64, double)** %p) {
+ %f = load i32 (i32, float, i64, double)*, i32 (i32, float, i64, double)** %p
+ %v = tail call i32 %f(i32 0, float 0., i64 0, double 0.)
+ ret i32 %v
+}
+
; CHECK-LABEL: .section .custom_section.target_features
; CHECK-NEXT: .int8 1
; CHECK-NEXT: .int8 43
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