cranelift: Translate stack_* accesses as unaligned (#6016)

We can't currently ensure that these will be aligned, so we shouldn't mark them as such.
bytecodealliance · Mar 15, 2023 · a10c50a · a10c50a
1 parent 6ed90f8
commit a10c50a
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Showing 3 changed files with 23 additions and 5 deletions.
diff --git a/cranelift/codegen/src/legalizer/mod.rs b/cranelift/codegen/src/legalizer/mod.rs
@@ -82,8 +82,10 @@ pub fn simple_legalize(func: &mut ir::Function, cfg: &mut ControlFlowGraph, isa:
 
                     let addr = pos.ins().stack_addr(addr_ty, stack_slot, offset);
 
-                    // Stack slots are required to be accessible and aligned.
-                    let mflags = MemFlags::trusted();
+                    // Stack slots are required to be accessible.
+                    // We can't currently ensure that they are aligned.
+                    let mut mflags = MemFlags::new();
+                    mflags.set_notrap();
                     pos.func.dfg.replace(inst).load(ty, mflags, addr, 0);
                 }
                 InstructionData::StackStore {
@@ -99,10 +101,10 @@ pub fn simple_legalize(func: &mut ir::Function, cfg: &mut ControlFlowGraph, isa:
 
                     let addr = pos.ins().stack_addr(addr_ty, stack_slot, offset);
 
+                    // Stack slots are required to be accessible.
+                    // We can't currently ensure that they are aligned.
                     let mut mflags = MemFlags::new();
-                    // Stack slots are required to be accessible and aligned.
                     mflags.set_notrap();
-                    mflags.set_aligned();
                     pos.func.dfg.replace(inst).store(mflags, arg, addr, 0);
                 }
                 InstructionData::DynamicStackLoad {

diff --git a/cranelift/filetests/filetests/egraph/misc.clif b/cranelift/filetests/filetests/egraph/misc.clif
@@ -16,6 +16,6 @@ block0(v0: i64):
 ; nextln:    ss0 = explicit_slot 8
 ; check:  block0(v0: i64):
 ; nextln:     v2 = stack_addr.i64 ss0
-; nextln:     store notrap aligned v0, v2
+; nextln:     store notrap v0, v2
 ; nextln:     return v0
 ; nextln: }
diff --git a/cranelift/filetests/filetests/runtests/simd-extractlane.clif b/cranelift/filetests/filetests/runtests/simd-extractlane.clif
@@ -100,3 +100,19 @@ block0(v0: f64x2):
     return v4
 }
 ; run: %extractlane_f64x2_through_stack([0x1.0 0x2.0]) == 0x1.0
+
+
+function %unaligned_extractlane() -> f64 {
+    ss0 = explicit_slot 24
+
+block0:
+    v0 = iconst.i64 0
+    stack_store.i64 v0, ss0+0
+    stack_store.i64 v0, ss0+8
+    stack_store.i64 v0, ss0+16
+
+    v1 = stack_load.f64x2 ss0+1
+    v2 = extractlane v1, 1
+    return v2
+}
+; run: %unaligned_extractlane() == 0.0