T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge pull request #2197 from cfallin/fix-if-params

Browse Source 
Account for duplicated if-block params on `end` op in unreachable case.
This commit is contained in:
Chris Fallin
2020-09-14 17:39:46 -07:00
committed by GitHub
parent 43d2799fa2 a0646c8d3f
commit 539815ef12
3 changed files with 55 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
cranelift/wasm/src/code_translator.rs
View File

@@ -332,24 +332,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
builder.seal_block(header)
}
// The "If" frame pushes its parameters twice, so they're available to the else block
// (see also `FuncTranslationState::push_if`).
// Yet, the original_stack_size member accounts for them only once, so that the else
// block can see the same number of parameters as the consequent block. As a matter of
// fact, we need to substract an extra number of parameter values for if blocks.
let num_duplicated_params = if let ControlStackFrame::If {
num_param_values, ..
} = frame
{
debug_assert!(num_param_values <= frame.original_stack_size());
num_param_values
} else {
0
};
state
.stack
.truncate(frame.original_stack_size() - num_duplicated_params);
frame.truncate_value_stack_to_original_size(&mut state.stack);
state
.stack
.extend_from_slice(builder.block_params(next_block));
@@ -1908,9 +1891,8 @@ fn translate_unreachable_operator<FE: FuncEnvironment + ?Sized>(
let (params, _results) =
blocktype_params_results(module_translation_state, blocktype)?;
let else_block = block_with_params(builder, params, environ)?;
state.stack.truncate(
state.control_stack.last().unwrap().original_stack_size(),
);
let frame = state.control_stack.last().unwrap();
frame.truncate_value_stack_to_else_params(&mut state.stack);
// We change the target of the branch instruction.
builder.change_jump_destination(branch_inst, else_block);
@@ -1918,9 +1900,8 @@ fn translate_unreachable_operator<FE: FuncEnvironment + ?Sized>(
else_block
}
ElseData::WithElse { else_block } => {
state.stack.truncate(
state.control_stack.last().unwrap().original_stack_size(),
);
let frame = state.control_stack.last().unwrap();
frame.truncate_value_stack_to_else_params(&mut state.stack);
else_block
}
};
@@ -1941,9 +1922,8 @@ fn translate_unreachable_operator<FE: FuncEnvironment + ?Sized>(
let control_stack = &mut state.control_stack;
let frame = control_stack.pop().unwrap();
// Now we have to split off the stack the values not used
// by unreachable code that hasn't been translated
stack.truncate(frame.original_stack_size());
// Pop unused parameters from stack.
frame.truncate_value_stack_to_original_size(stack);
let reachable_anyway = match frame {
// If it is a loop we also have to seal the body loop block

31
cranelift/wasm/src/state/func_state.rs
View File

@@ -128,7 +128,9 @@ impl ControlStackFrame {
Self::Loop { header, .. } => header,
}
}
pub fn original_stack_size(&self) -> usize {
/// Private helper. Use `truncate_value_stack_to_else_params()` or
/// `truncate_value_stack_to_original_size()` to restore value-stack state.
fn original_stack_size(&self) -> usize {
match *self {
Self::If {
original_stack_size,
@@ -178,6 +180,33 @@ impl ControlStackFrame {
Self::Loop { .. } => {}
}
}
/// Pop values from the value stack so that it is left at the
/// input-parameters to an else-block.
pub fn truncate_value_stack_to_else_params(&self, stack: &mut Vec<Value>) {
debug_assert!(matches!(self, &ControlStackFrame::If { .. }));
stack.truncate(self.original_stack_size());
}
/// Pop values from the value stack so that it is left at the state it was
/// before this control-flow frame.
pub fn truncate_value_stack_to_original_size(&self, stack: &mut Vec<Value>) {
// The "If" frame pushes its parameters twice, so they're available to the else block
// (see also `FuncTranslationState::push_if`).
// Yet, the original_stack_size member accounts for them only once, so that the else
// block can see the same number of parameters as the consequent block. As a matter of
// fact, we need to substract an extra number of parameter values for if blocks.
let num_duplicated_params = match self {
&ControlStackFrame::If {
num_param_values, ..
} => {
debug_assert!(num_param_values <= self.original_stack_size());
num_param_values
}
_ => 0,
};
stack.truncate(self.original_stack_size() - num_duplicated_params);
}
}
/// Contains information passed along during a function's translation and that records:

18
cranelift/wasmtests/if-unreachable-else-params-2.wat Normal file
View File

@@ -0,0 +1,18 @@
(module
(type (;0;) (func (param i32 i32) (result f64)))
(func $main (type 0) (param i32 i32) (result f64)
f64.const 1.0
local.get 0
local.get 1
if (param i32) ;; label = @2
i64.load16_s align=1
drop
else
unreachable
end)
(table (;0;) 63 255 funcref)
(memory (;0;) 13 16)
(export "t1" (table 0))
(export "m1" (memory 0))
(export "main" (func $main))
(export "memory" (memory 0)))