implement the gas opcode (#136)

Cargo.toml

@@ -68,7 +68,7 @@ git2 = "0.19.0"
 # polkadot-sdk and friends
 codec = { version = "3.6.12", default-features = false, package = "parity-scale-codec" }
 scale-info = { version = "2.11.1", default-features = false }
-polkadot-sdk = { git = "https://github.com/paritytech/polkadot-sdk", rev = "4a0e3f624f42816cb4ca687d3ff9bba8e1a6bf19" }
+polkadot-sdk = { git = "https://github.com/paritytech/polkadot-sdk", rev = "6ad748857e0e63c38cb7bb9435831ae73ab708cf" }
 
 # llvm
 [workspace.dependencies.inkwell]

crates/integration/codesize.json

@@ -1,10 +1,10 @@
 {
-  "Baseline": 1126,
-  "Computation": 2405,
-  "DivisionArithmetics": 14486,
-  "ERC20": 22755,
-  "Events": 1620,
-  "FibonacciIterative": 1670,
-  "Flipper": 2005,
-  "SHA1": 16832
+  "Baseline": 1115,
+  "Computation": 2394,
+  "DivisionArithmetics": 14470,
+  "ERC20": 22747,
+  "Events": 1609,
+  "FibonacciIterative": 1659,
+  "Flipper": 1994,
+  "SHA1": 16817
 }

crates/integration/contracts/GasLeft.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8;
+
+/* runner.json
+{
+    "differential": false,
+    "actions": [
+        {
+            "Instantiate": {
+                "code": {
+                    "Solidity": {
+                        "contract": "GasLeft"
+                    }
+                }
+            }
+        },
+        {
+            "VerifyCall": {
+                "success": true
+            }
+        }
+    ]
+}
+*/
+
+contract GasLeft {
+    constructor() payable {
+        assert(gasleft() > gasleft());
+        assert(gasleft() > 0 && gasleft() < 0xffffffffffffffff);
+    }
+}

crates/integration/src/tests.rs

@@ -47,6 +47,7 @@ test_spec!(transaction, "Transaction", "Transaction.sol");
 test_spec!(block_hash, "BlockHash", "BlockHash.sol");
 test_spec!(delegate, "Delegate", "Delegate.sol");
 test_spec!(gas_price, "GasPrice", "GasPrice.sol");
+test_spec!(gas_left, "GasLeft", "GasLeft.sol");
 
 fn instantiate(path: &str, contract: &str) -> Vec<SpecsAction> {
     vec![Instantiate {

crates/llvm-context/src/polkavm/evm/ether_gas.rs

@@ -1,7 +1,5 @@
 //! Translates the value and balance operations.
 
-use inkwell::values::BasicValue;
-
 use crate::polkavm::context::Context;
 use crate::polkavm::Dependency;
 
@@ -12,7 +10,15 @@ pub fn gas<'ctx, D>(
 where
     D: Dependency + Clone,
 {
-    Ok(context.integer_const(256, 0).as_basic_value_enum())
+    let ref_time_left_value = context
+        .build_runtime_call(revive_runtime_api::polkavm_imports::REF_TIME_LEFT, &[])
+        .expect("the ref_time_left syscall method should return a value")
+        .into_int_value();
+
+    Ok(context
+        .builder()
+        .build_int_z_extend(ref_time_left_value, context.word_type(), "gas_left")?
+        .into())
 }
 
 /// Translates the `value` instruction.

crates/runtime-api/src/polkavm_imports.c

@@ -108,7 +108,7 @@ POLKAVM_IMPORT(void, origin, uint32_t)
 
 POLKAVM_IMPORT(void, seal_return, uint32_t, uint32_t, uint32_t)
 
-POLKAVM_IMPORT(uint64_t, set_storage, uint32_t, uint32_t, uint32_t, uint32_t, uint32_t)
+POLKAVM_IMPORT(uint64_t, ref_time_left)
 
 POLKAVM_IMPORT(void, return_data_copy, uint32_t, uint32_t, uint32_t)
 
@@ -116,6 +116,8 @@ POLKAVM_IMPORT(void, return_data_size, uint32_t)
 
 POLKAVM_IMPORT(void, set_immutable_data, uint32_t, uint32_t);
 
+POLKAVM_IMPORT(uint64_t, set_storage, uint32_t, uint32_t, uint32_t, uint32_t, uint32_t)
+
 POLKAVM_IMPORT(void, value_transferred, uint32_t)
 
 POLKAVM_IMPORT(void, weight_to_fee, uint64_t, uint64_t, uint32_t);

crates/runtime-api/src/polkavm_imports.rs

@@ -56,9 +56,9 @@ pub static NOW: &str = "now";
 
 pub static ORIGIN: &str = "origin";
 
-pub static RETURN: &str = "seal_return";
+pub static REF_TIME_LEFT: &str = "ref_time_left";
 
-pub static SET_STORAGE: &str = "set_storage";
+pub static RETURN: &str = "seal_return";
 
 pub static RETURNDATACOPY: &str = "return_data_copy";
 
@@ -66,13 +66,15 @@ pub static RETURNDATASIZE: &str = "return_data_size";
 
 pub static SET_IMMUTABLE_DATA: &str = "set_immutable_data";
 
+pub static SET_STORAGE: &str = "set_storage";
+
 pub static VALUE_TRANSFERRED: &str = "value_transferred";
 
 pub static WEIGHT_TO_FEE: &str = "weight_to_fee";
 
 /// All imported runtime API symbols.
 /// Useful for configuring common attributes and linkage.
-pub static IMPORTS: [&str; 30] = [
+pub static IMPORTS: [&str; 31] = [
     SBRK,
     MEMORY_SIZE,
     ADDRESS,
@@ -96,6 +98,7 @@ pub static IMPORTS: [&str; 30] = [
     INSTANTIATE,
     NOW,
     ORIGIN,
+    REF_TIME_LEFT,
     RETURN,
     RETURNDATACOPY,
     RETURNDATASIZE,