[X86] Do not elect to tail call if caller must preserve all registers

A miscompilation issue has been addressed with improved checking.

Fixes: llvm#97758.

Author: antoniofrighetto

llvm/lib/Target/X86/X86ISelLoweringCall.cpp

@@ -2856,6 +2856,13 @@ bool X86TargetLowering::IsEligibleForTailCallOptimization(
       return false;
   }
 
+  // The stack frame of the caller cannot be replaced by the tail-callee one's
+  // if the function is required to preserve all the registers. Conservatively
+  // prevent tail optimization even if hypothetically all the registers are used
+  // for passing formal parameters or returning values.
+  if (CallerF.hasFnAttribute("no_caller_saved_registers"))
+    return false;
+
   unsigned StackArgsSize = CCInfo.getStackSize();
 
   // If the callee takes no arguments then go on to check the results of the

llvm/test/CodeGen/X86/tailcall-caller-nocsr.ll

@@ -13,16 +13,18 @@ define void @caller(i32 %0, i32 %1) #0 {
 ; CHECK-NEXT:    pushq %rdx
 ; CHECK-NEXT:    pushq %rcx
 ; CHECK-NEXT:    pushq %rax
+; CHECK-NEXT:    movl %esi, %edx
 ; CHECK-NEXT:    movl %edi, %esi
 ; CHECK-NEXT:    movl $.L.str, %edi
+; CHECK-NEXT:    callq printf@PLT
 ; CHECK-NEXT:    popq %rax
 ; CHECK-NEXT:    popq %rcx
 ; CHECK-NEXT:    popq %rdx
 ; CHECK-NEXT:    popq %r8
 ; CHECK-NEXT:    popq %r9
 ; CHECK-NEXT:    popq %r10
 ; CHECK-NEXT:    popq %r11
-; CHECK-NEXT:    jmp printf@PLT # TAILCALL
+; CHECK-NEXT:    retq
   %3 = tail call i32 @printf(ptr @.str, i32 %0, i32 %1)
   ret void
 }