[NFC][SelectionDAG] Replace generic @llvm.expect.with.probability codegen test with X86 test (#117848)

Adds test case for X86 to check that the output of
@llvm.expect.with.probability's generic lowering is reasonable. This
replaces a generic test which only asserts that llc does not crash.

Author: antangelo

llvm/test/CodeGen/Generic/builtin-expect-with-probability.ll

@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
 ; RUN: llc < %s -O0 | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
@@ -6,9 +7,17 @@ target triple = "i686-unknown-linux-gnu"
 @glbl = extern_weak constant i8
 
 declare i64 @llvm.expect.i64(i64, i64)
+declare i64 @llvm.expect.with.probability.i64(i64, i64, double)
 
-define void @test() {
-; CHECK: movl $glbl
+define void @test_expect() {
+; CHECK-LABEL: test_expect:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl $glbl, %eax
+; CHECK-NEXT:    testl %eax, %eax
+; CHECK-NEXT:    jne .LBB0_2
+; CHECK-NEXT:    jmp .LBB0_1
+; CHECK-NEXT:  .LBB0_1: # %bb1
+; CHECK-NEXT:  .LBB0_2: # %bb2
   %cmp2 = icmp eq ptr @glbl, null
   %ext = zext i1 %cmp2 to i64
   %tmp = call i64 @llvm.expect.i64(i64 %ext, i64 0)
@@ -21,3 +30,25 @@ bb1:
 bb2:
   unreachable
 }
+
+define void @test_expect_with_probability() {
+; CHECK-LABEL: test_expect_with_probability:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl $glbl, %eax
+; CHECK-NEXT:    testl %eax, %eax
+; CHECK-NEXT:    jne .LBB1_2
+; CHECK-NEXT:    jmp .LBB1_1
+; CHECK-NEXT:  .LBB1_1: # %bb1
+; CHECK-NEXT:  .LBB1_2: # %bb2
+  %cmp2 = icmp eq ptr @glbl, null
+  %ext = zext i1 %cmp2 to i64
+  %tmp = call i64 @llvm.expect.with.probability.i64(i64 %ext, i64 0, double 0.5)
+  %tmp2 = icmp ne i64 %tmp, 0
+  br i1 %tmp2, label %bb1, label %bb2
+
+bb1:
+  unreachable
+
+bb2:
+  unreachable
+}