From 6af407144c6441720b2953d080455e565ee81b0e Mon Sep 17 00:00:00 2001
From: Dan Gohman <sunfish@mozilla.com>
Date: Tue, 28 Aug 2018 12:36:21 -0700
Subject: [PATCH] Remove `Signature`'s `argument_bytes` field.

It's not currently used. If we do need such information, it would be
better to compute it on demand.
---
 cranelift/tests/moduletests.rs        |  2 --
 lib/codegen/src/ir/extfunc.rs         | 37 +--------------------------
 lib/codegen/src/legalizer/boundary.rs |  1 -
 lib/codegen/src/verifier/mod.rs       |  5 ----
 lib/reader/src/parser.rs              |  4 ---
 5 files changed, 1 insertion(+), 48 deletions(-)

diff --git a/cranelift/tests/moduletests.rs b/cranelift/tests/moduletests.rs
index c2312fe4f2..a4aea4b389 100644
--- a/cranelift/tests/moduletests.rs
+++ b/cranelift/tests/moduletests.rs
@@ -19,7 +19,6 @@ fn error_on_incompatible_sig_in_declare_function() {
         params: vec![AbiParam::new(types::I64)],
         returns: vec![],
         call_conv: CallConv::SystemV,
-        argument_bytes: None,
     };
     module
         .declare_function("abc", Linkage::Local, &sig)
@@ -36,7 +35,6 @@ fn define_simple_function(module: &mut Module<SimpleJITBackend>) -> FuncId {
         params: vec![],
         returns: vec![],
         call_conv: CallConv::SystemV,
-        argument_bytes: None,
     };
 
     let func_id = module
diff --git a/lib/codegen/src/ir/extfunc.rs b/lib/codegen/src/ir/extfunc.rs
index 30f0eaab74..451a90a7f9 100644
--- a/lib/codegen/src/ir/extfunc.rs
+++ b/lib/codegen/src/ir/extfunc.rs
@@ -8,7 +8,6 @@
 use ir::{ArgumentLoc, ExternalName, SigRef, Type};
 use isa::{RegInfo, RegUnit};
 use settings::CallConv;
-use std::cmp;
 use std::fmt;
 use std::str::FromStr;
 use std::vec::Vec;
@@ -29,13 +28,6 @@ pub struct Signature {
 
     /// Calling convention.
     pub call_conv: CallConv,
-
-    /// When the signature has been legalized to a specific ISA, this holds the size of the
-    /// argument array on the stack. Before legalization, this is `None`.
-    ///
-    /// This can be computed from the legalized `params` array as the maximum (offset plus
-    /// byte size) of the `ArgumentLoc::Stack(offset)` argument.
-    pub argument_bytes: Option<u32>,
 }
 
 impl Signature {
@@ -45,7 +37,6 @@ impl Signature {
             params: Vec::new(),
             returns: Vec::new(),
             call_conv,
-            argument_bytes: None,
         }
     }
 
@@ -54,25 +45,6 @@ impl Signature {
         self.params.clear();
         self.returns.clear();
         self.call_conv = call_conv;
-        self.argument_bytes = None;
-    }
-
-    /// Compute the size of the stack arguments and mark signature as legalized.
-    ///
-    /// Even if there are no stack arguments, this will set `params` to `Some(0)` instead
-    /// of `None`. This indicates that the signature has been legalized.
-    pub fn compute_argument_bytes(&mut self) {
-        let bytes = self
-            .params
-            .iter()
-            .filter_map(|arg| match arg.location {
-                ArgumentLoc::Stack(offset) if offset >= 0 => {
-                    Some(offset as u32 + arg.value_type.bytes())
-                }
-                _ => None,
-            })
-            .fold(0, cmp::max);
-        self.argument_bytes = Some(bytes);
     }
 
     /// Return an object that can display `self` with correct register names.
@@ -421,16 +393,9 @@ mod tests {
         sig.returns.push(AbiParam::new(B8));
         assert_eq!(sig.to_string(), "(i32, i32x4) -> f32, b8 baldrdash");
 
-        // Test the offset computation algorithm.
-        assert_eq!(sig.argument_bytes, None);
-        sig.params[1].location = ArgumentLoc::Stack(8);
-        sig.compute_argument_bytes();
-        // An `i32x4` at offset 8 requires a 24-byte argument array.
-        assert_eq!(sig.argument_bytes, Some(24));
         // Order does not matter.
         sig.params[0].location = ArgumentLoc::Stack(24);
-        sig.compute_argument_bytes();
-        assert_eq!(sig.argument_bytes, Some(28));
+        sig.params[1].location = ArgumentLoc::Stack(8);
 
         // Writing ABI-annotated signatures.
         assert_eq!(
diff --git a/lib/codegen/src/legalizer/boundary.rs b/lib/codegen/src/legalizer/boundary.rs
index 6f3143028b..e052e63be6 100644
--- a/lib/codegen/src/legalizer/boundary.rs
+++ b/lib/codegen/src/legalizer/boundary.rs
@@ -57,7 +57,6 @@ pub fn legalize_libcall_signature(signature: &mut Signature, isa: &TargetIsa) {
 /// `current` is true if this is the signature for the current function.
 fn legalize_signature(signature: &mut Signature, current: bool, isa: &TargetIsa) {
     isa.legalize_signature(signature, current);
-    signature.compute_argument_bytes();
 }
 
 /// Legalize the entry block parameters after `func`'s signature has been legalized.
diff --git a/lib/codegen/src/verifier/mod.rs b/lib/codegen/src/verifier/mod.rs
index bce49501e3..2f9c1dbcb4 100644
--- a/lib/codegen/src/verifier/mod.rs
+++ b/lib/codegen/src/verifier/mod.rs
@@ -1160,11 +1160,6 @@ impl<'a> Verifier<'a> {
     ) -> VerifierStepResult<()> {
         let sig = &self.func.dfg.signatures[sig_ref];
 
-        // Before legalization, there's nothing to check.
-        if sig.argument_bytes.is_none() {
-            return Ok(());
-        }
-
         let args = self.func.dfg.inst_variable_args(inst);
         let expected_args = &sig.params[..];
 
diff --git a/lib/reader/src/parser.rs b/lib/reader/src/parser.rs
index ff155fc195..c5bbe47f8f 100644
--- a/lib/reader/src/parser.rs
+++ b/lib/reader/src/parser.rs
@@ -919,10 +919,6 @@ impl<'a> Parser<'a> {
             }
         }
 
-        if sig.params.iter().all(|a| a.location.is_assigned()) {
-            sig.compute_argument_bytes();
-        }
-
         Ok(sig)
     }