[llvm] bd7ca98 - Ensure NoTrapAfterNoreturn is false for the wasm backend (#65876)
via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 5 09:17:49 PDT 2023
Author: Matt Harding
Date: 2023-10-05T09:17:45-07:00
New Revision: bd7ca98b66700925625ae84aa1083e94a3b875aa
URL: https://github.com/llvm/llvm-project/commit/bd7ca98b66700925625ae84aa1083e94a3b875aa
DIFF: https://github.com/llvm/llvm-project/commit/bd7ca98b66700925625ae84aa1083e94a3b875aa.diff
LOG: Ensure NoTrapAfterNoreturn is false for the wasm backend (#65876)
In the WebAssembly back end, the TrapUnreachable option is currently
load-bearing for correctness, inserting wasm `unreachable` instructions
where needed to create valid wasm. There is another option,
NoTrapAfterNoreturn, that removes some of those traps and causes
incorrect wasm to be emitted.
This turns off `NoTrapAfterNoreturn` for the Wasm backend and adds new
tests.
Added:
Modified:
llvm/include/llvm/CodeGen/MachineFunction.h
llvm/include/llvm/CodeGen/MachineInstr.h
llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
llvm/test/CodeGen/WebAssembly/unreachable.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
index 6c2da626ea54b4d..8f1651c2958e591 100644
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -266,7 +266,7 @@ class LLVM_EXTERNAL_VISIBILITY MachineFunction {
// RegInfo - Information about each register in use in the function.
MachineRegisterInfo *RegInfo;
- // Used to keep track of target-specific per-machine function information for
+ // Used to keep track of target-specific per-machine-function information for
// the target implementation.
MachineFunctionInfo *MFInfo;
diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index 03fb15f77c65cbb..8367f999fcc76d3 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1276,7 +1276,7 @@ class MachineInstr
/// eraseFromBundle() to erase individual bundled instructions.
void eraseFromParent();
- /// Unlink 'this' form its basic block and delete it.
+ /// Unlink 'this' from its basic block and delete it.
///
/// If the instruction is part of a bundle, the other instructions in the
/// bundle remain bundled.
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
index 131e99c66fa2e5a..d8cbddf74545da6 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -667,7 +667,7 @@ void WebAssemblyCFGStackify::removeUnnecessaryInstrs(MachineFunction &MF) {
// When there is an unconditional branch right before a catch instruction and
// it branches to the end of end_try marker, we don't need the branch, because
- // it there is no exception, the control flow transfers to that point anyway.
+ // if there is no exception, the control flow transfers to that point anyway.
// bb0:
// try
// ...
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 10464e8f52e5612..88c727796e0dfd7 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -127,6 +127,7 @@ WebAssemblyTargetMachine::WebAssemblyTargetMachine(
// LLVM 'unreachable' to ISD::TRAP and then lower that to WebAssembly's
// 'unreachable' instructions which is meant for that case.
this->Options.TrapUnreachable = true;
+ this->Options.NoTrapAfterNoreturn = false;
// WebAssembly treats each function as an independent unit. Force
// -ffunction-sections, effectively, so that we can emit them independently.
diff --git a/llvm/test/CodeGen/WebAssembly/unreachable.ll b/llvm/test/CodeGen/WebAssembly/unreachable.ll
index ad1c90090ac58bf..72f865842bdcaa5 100644
--- a/llvm/test/CodeGen/WebAssembly/unreachable.ll
+++ b/llvm/test/CodeGen/WebAssembly/unreachable.ll
@@ -1,33 +1,97 @@
-; RUN: llc < %s -asm-verbose=false -verify-machineinstrs | FileCheck %s
-; RUN: llc < %s -asm-verbose=false -fast-isel -fast-isel-abort=1 -verify-machineinstrs | FileCheck %s
+; The assertions in this file were autogenerated by
+; utils/update_llc_test_checks.py, but were hand-edited to add the
+; "end_function" lines to prevent the tests from passing when there are
+; superfluous instructions at the end of a function. You can run
+; update_llc_test_checks.py again, but please keep the "end_function" lines
+; intact when you commit.
-; Test that LLVM unreachable instruction and trap intrinsic are lowered to
-; wasm unreachable
+; Wasm, to generate valid code, always internally sets `--trap-unreachable` to 1
+; and `--no-trap-after-noreturn` to 0, and these command lines options, if
+; explicitly given, are ignored. Various combinations of these options should
+; have no effect and should not generate invalid code.
+; RUN: llc < %s -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -verify-machineinstrs --trap-unreachable | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs --trap-unreachable | FileCheck %s
+; RUN: llc < %s -verify-machineinstrs --trap-unreachable --no-trap-after-noreturn | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs --trap-unreachable --no-trap-after-noreturn | FileCheck %s
target triple = "wasm32-unknown-unknown"
-declare void @llvm.trap()
-declare void @llvm.debugtrap()
-declare void @abort()
-; CHECK-LABEL: f1:
-; CHECK: call abort{{$}}
-; CHECK: unreachable
-define i32 @f1() {
- call void @abort()
- unreachable
-}
+; Test that the LLVM trap and debug trap intrinsics are lowered to wasm
+; unreachable.
-; CHECK-LABEL: f2:
-; CHECK: unreachable
-define void @f2() {
+declare void @llvm.trap() cold noreturn nounwind
+declare void @llvm.debugtrap() nounwind
+
+define void @trap_ret_void() {
+; CHECK-LABEL: trap_ret_void:
+; CHECK: .functype trap_ret_void () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: # fallthrough-return
+; CHECK-NEXT: end_function
call void @llvm.trap()
ret void
}
-; CHECK-LABEL: f3:
-; CHECK: unreachable
-define void @f3() {
+define void @debugtrap_ret_void() {
+; CHECK-LABEL: debugtrap_ret_void:
+; CHECK: .functype debugtrap_ret_void () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: # fallthrough-return
+; CHECK-NEXT: end_function
call void @llvm.debugtrap()
ret void
}
+
+; LLVM trap followed by LLVM unreachable could become exactly one wasm
+; unreachable, but two are emitted currently.
+define void @trap_unreacheable() {
+; CHECK-LABEL: trap_unreacheable:
+; CHECK: .functype trap_unreacheable () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: end_function
+ call void @llvm.trap()
+ unreachable
+}
+
+
+; Test that LLVM unreachable instruction is lowered to wasm unreachable when
+; necessary to fulfill the wasm operand stack requirements.
+
+declare void @ext_func()
+declare i32 @ext_func_i32()
+declare void @ext_never_return() noreturn
+
+; LLVM IR's 'unreachable' is translated to Wasm 'unreachable'.
+define i32 @missing_ret_unreachable() {
+; CHECK-LABEL: missing_ret_unreachable:
+; CHECK: .functype missing_ret_unreachable () -> (i32)
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: call ext_func
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: end_function
+ call void @ext_func()
+ unreachable
+}
+
+; This is similar to the above test, but ensures wasm unreachable is emitted
+; This is similar to the above test, but the callee has a 'noreturn' attribute.
+; There is an optimization that removes an 'unreachable' after a noreturn call,
+; but Wasm backend doesn't use it and ignore `--no-trap-after-noreturn`, if
+; given, to generate valid code.
+define i32 @missing_ret_noreturn_unreachable() {
+; CHECK-LABEL: missing_ret_noreturn_unreachable:
+; CHECK: .functype missing_ret_noreturn_unreachable () -> (i32)
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: call ext_never_return
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: end_function
+ call void @ext_never_return()
+ unreachable
+}
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