Build and test wasmtime-fiber on i686/arm (#9035)

Now that we've got CI for Pulley throw in `wasmtime-fiber` as well with
a few extra fixes. This should also help improve the compilation
experience of Wasmtime to 32-bit platforms to hit a more first-class
error about unsupported platforms.

ci/build-test-matrix.js

@@ -26,6 +26,15 @@ const FAST_MATRIX = [
   },
 ];
 
+// Returns whether the given package supports a 32-bit architecture, used when
+// testing on i686 and armv7 below.
+function supports32Bit(pkg) {
+  if (pkg.indexOf("pulley") !== -1)
+    return true;
+
+  return pkg == 'wasmtime-fiber';
+}
+
 // This is the full, unsharded, and unfiltered matrix of what we test on
 // CI. This includes a number of platforms and a number of cross-compiled
 // targets that are emulated with QEMU. This must be kept tightly in sync with
@@ -123,16 +132,15 @@ const FULL_MATRIX = [
     "isa": "riscv64",
   },
   {
-    "name": "Test Pulley on i686-unknown-linux-gnu",
+    "name": "Tests on i686-unknown-linux-gnu",
     "32-bit": true,
     "os": "ubuntu-latest",
     "target": "i686-unknown-linux-gnu",
     "gcc_package": "gcc-i686-linux-gnu",
     "gcc": "i686-linux-gnu-gcc",
-    "filter": "pulley",
   },
   {
-    "name": "Test Pulley on armv7-unknown-linux-gnueabihf",
+    "name": "Tests on armv7-unknown-linux-gnueabihf",
     "32-bit": true,
     "os": "ubuntu-latest",
     "target": "armv7-unknown-linux-gnueabihf",
@@ -140,7 +148,6 @@ const FULL_MATRIX = [
     "gcc": "arm-linux-gnueabihf-gcc",
     "qemu": "qemu-arm -L /usr/arm-linux-gnueabihf -E LD_LIBRARY_PATH=/usr/arm-linux-gnueabihf/lib",
     "qemu_target": "arm-linux-user",
-    "filter": "pulley",
   },
 ];
 
@@ -218,14 +225,16 @@ async function shard(configs) {
   // created above.
   const sharded = [];
   for (const config of configs) {
-    // Special case 32-bit configs. Only Pulley runs on 32-bit targets.
+    // Special case 32-bit configs. Only some crates, according to
+    // `supports32Bit`, run on this target. At this time the set of supported
+    // crates is small enough that they're not sharded.
     if (config["32-bit"] === true) {
       sharded.push(Object.assign(
         {},
         config,
         {
           bucket: members
-            .map(c => c.indexOf("pulley") !== -1 ? `--package ${c}` : `--exclude ${c}`)
+            .map(c => supports32Bit(c) ? `--package ${c}` : `--exclude ${c}`)
             .join(" "),
         }
       ));
@@ -290,9 +299,14 @@ async function main() {
         return true;
     }
 
-    // If any Pulley source file was modified, then run Pulley-specific configs.
-    if (names.includes("pulley") && config.filter == "pulley") {
-      return true;
+    // For matrix entries that represent 32-bit only some crates support that,
+    // so whenever the crates are changed be sure to run 32-bit tests on PRs
+    // too.
+    if (config["32-bit"] === true) {
+      if (names.includes("pulley"))
+        return true;
+      if (names.includes("fiber"))
+        return true;
     }
 
     // If the commit explicitly asks for this test config, then include it.

crates/fiber/src/lib.rs

@@ -283,6 +283,9 @@ mod tests {
                 || cfg!(windows)
                 // TODO: the system libunwind is broken (#2808)
                 || cfg!(all(target_os = "macos", target_arch = "aarch64"))
+                // TODO: see comments in `arm.rs` about how this seems to work
+                // in gdb but not at runtime, unsure why at this time.
+                || cfg!(target_arch = "arm")
             );
         }
 

crates/fiber/src/unix/arm.rs

@@ -8,7 +8,7 @@
 // Also at this time this file is heavily based off the x86_64 file, so you'll
 // probably want to read that one as well.
 
-use wasmtime_asm_macros::{asm_func, asm_sym};
+use wasmtime_asm_macros::asm_func;
 
 // fn(top_of_stack(%r0): *mut u8)
 asm_func!(
@@ -36,7 +36,7 @@ asm_func!(
 asm_func!(
     wasmtime_versioned_export_macros::versioned_stringify_ident!(wasmtime_fiber_init),
     "
-        adr r3, wasmtime_fiber_start
+        adr r3, {start}
         str r3, [r0, #-0x0c] // => lr
         str r0, [r0, #-0x10] // => r11
         str r1, [r0, #-0x14] // => r10
@@ -46,6 +46,7 @@ asm_func!(
         str r3, [r0, #-0x08]
         bx lr
     ",
+    start = sym super::wasmtime_fiber_start,
 );
 
 asm_func!(

crates/fiber/src/unix/x86.rs

@@ -10,11 +10,11 @@
 // different so the reserved space at the top of the stack is 8 bytes, not 16
 // bytes. Still two pointers though.
 
-use wasmtime_asm_macros::{asm_func, asm_sym};
+use wasmtime_asm_macros::asm_func;
 
 // fn(top_of_stack: *mut u8)
 asm_func!(
-    "wasmtime_fiber_switch",
+    wasmtime_versioned_export_macros::versioned_stringify_ident!(wasmtime_fiber_switch),
     "
         // Load our stack-to-use
         mov eax, 0x4[esp]
@@ -45,7 +45,7 @@ asm_func!(
 //    entry_arg0: *mut u8,
 // )
 asm_func!(
-    "wasmtime_fiber_init",
+    wasmtime_versioned_export_macros::versioned_stringify_ident!(wasmtime_fiber_init),
     "
         mov eax, 4[esp]
 
@@ -58,8 +58,7 @@ asm_func!(
 
         // Move our start function to the return address which the `ret` in
         // `wasmtime_fiber_start` will return to.
-        lea ecx, wasmtime_fiber_start2
-        lea ecx, wasmtime_fiber_start
+        lea ecx, {start}
         mov -0x14[eax], ecx
 
         // And move `entry_point` to get loaded into `%ebp` through the context
@@ -81,10 +80,11 @@ asm_func!(
         mov -0x08[eax], ecx
         ret
     ",
+    start = sym super::wasmtime_fiber_start,
 );
 
 asm_func!(
-    "wasmtime_fiber_start",
+    wasmtime_versioned_export_macros::versioned_stringify_ident!(wasmtime_fiber_start),
     "
         .cfi_startproc simple
         .cfi_def_cfa_offset 0