[WebAssembly] Guard use of getSymbolName with isSymbol (#156105)

WebAssemblyRegStackfy checks for writes to the stack pointer to avoid
stackifying across them, but it wasn't prepared for other global_set
instructions (such as writes in addrspace 1).

Fixes #156055

Thanks to @QuantumSegfault for reporting and identifying the offending
code.

Author: dschuff

llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp

@@ -247,7 +247,8 @@ static void query(const MachineInstr &MI, bool &Read, bool &Write,
   // Check for writes to __stack_pointer global.
   if ((MI.getOpcode() == WebAssembly::GLOBAL_SET_I32 ||
        MI.getOpcode() == WebAssembly::GLOBAL_SET_I64) &&
-      strcmp(MI.getOperand(0).getSymbolName(), "__stack_pointer") == 0)
+      MI.getOperand(0).isSymbol() &&
+      !strcmp(MI.getOperand(0).getSymbolName(), "__stack_pointer"))
     StackPointer = true;
 
   // Analyze calls.

llvm/test/CodeGen/WebAssembly/global-set.ll

@@ -45,6 +45,22 @@ define void @set_f64_global(double %v) {
   ret void
 }
 
+declare i32 @get_i32()
+define i32 @stackifyAcrossGlobalSet() {
+; https://github.com/llvm/llvm-project/issues/156055
+; CHECK-LABEL: stackifyAcrossGlobalSet:
+; CHECK-NEXT: .functype
+; CHECK-NEXT: .local
+; CHECK-NEXT: call get_i32
+; CHECK-NEXT: local.tee
+; CHECK-NEXT: global.set i32_global
+; CHECK-NEXT: local.get
+; CHECK-NEXT: end_function
+  %1 = call i32 @get_i32()
+  store i32 %1, ptr addrspace(1) @i32_global
+  ret i32 %1
+}
+
 ; CHECK: .globaltype i32_global, i32
 ; CHECK: .globl i32_global
 ; CHECK-LABEL: i32_global: