[clang] [CIR][X86] Add MSVC bit scan builtins (PR #234304)

[Andy Kaylor via cfe-commits]

================
@@ -0,0 +1,76 @@
+// RUN: %clang_cc1 -x c -ffreestanding -fms-extensions \
+// RUN:   -Wno-implicit-function-declaration -fclangir \
+// RUN:   -triple x86_64-unknown-linux -emit-cir -o %t.cir %s
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+
+#ifdef __LP64__
+#define LONG int
+#else
+#define LONG long
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+unsigned char test_BitScanForward(unsigned LONG *Index, unsigned LONG Mask) {
+  return _BitScanForward(Index, Mask);
+}
+
+// CIR-LABEL: cir.func{{.*}}@test_BitScanForward
+// CIR: [[ZERO_FWD:%.*]] = cir.const #cir.int<0> : !u32i
+// CIR: [[NONZERO_FWD:%.*]] = cir.cmp ne {{%.*}}, [[ZERO_FWD]] : !u32i
+// CIR: cir.if [[NONZERO_FWD]] {
+// CIR: cir.ctz {{%.*}} poison_zero : !u32i
+// CIR: cir.store align(4) {{%.*}}, {{%.*}} : !u32i, !cir.ptr<!u32i>
+// CIR: cir.cast bool_to_int [[NONZERO_FWD]] : !cir.bool -> !u8i
+
+unsigned char test_BitScanReverse(unsigned LONG *Index, unsigned LONG Mask) {
+  return _BitScanReverse(Index, Mask);
+}
+
+// CIR-LABEL: cir.func{{.*}}@test_BitScanReverse
+// CIR: [[ZERO_REV:%.*]] = cir.const #cir.int<0> : !u32i
+// CIR: [[NONZERO_REV:%.*]] = cir.cmp ne {{%.*}}, [[ZERO_REV]] : !u32i
+// CIR: cir.if [[NONZERO_REV]] {
+// CIR: cir.const #cir.int<31> : !u32i
+// CIR: cir.clz {{%.*}} poison_zero : !u32i
+// CIR: cir.sub nsw {{%.*}}, {{%.*}} : !u32i
+// CIR: cir.store align(4) {{%.*}}, {{%.*}} : !u32i, !cir.ptr<!u32i>
+// CIR: cir.cast bool_to_int [[NONZERO_REV]] : !cir.bool -> !u8i
+
+#if defined(__x86_64__)
+unsigned char test_BitScanForward64(unsigned LONG *Index,
+                                    unsigned __int64 Mask) {
+  return _BitScanForward64(Index, Mask);
+}
+
+// CIR-LABEL: cir.func{{.*}}@test_BitScanForward64
+// CIR: [[ZERO_FWD64:%.*]] = cir.const #cir.int<0> : !u64i
+// CIR: [[NONZERO_FWD64:%.*]] = cir.cmp ne {{%.*}}, [[ZERO_FWD64]] : !u64i
+// CIR: cir.if [[NONZERO_FWD64]] {
+// CIR: cir.ctz {{%.*}} poison_zero : !u64i
+// CIR: cir.cast integral {{%.*}} : !u64i -> !u32i
+// CIR: cir.store align(4) {{%.*}}, {{%.*}} : !u32i, !cir.ptr<!u32i>
+// CIR: cir.cast bool_to_int [[NONZERO_FWD64]] : !cir.bool -> !u8i
+
+unsigned char test_BitScanReverse64(unsigned LONG *Index,
+                                    unsigned __int64 Mask) {
+  return _BitScanReverse64(Index, Mask);
+}
+
+// CIR-LABEL: cir.func{{.*}}@test_BitScanReverse64
+// CIR: [[ZERO_REV64:%.*]] = cir.const #cir.int<0> : !u64i
+// CIR: [[NONZERO_REV64:%.*]] = cir.cmp ne {{%.*}}, [[ZERO_REV64]] : !u64i
+// CIR: cir.if [[NONZERO_REV64]] {
+// CIR: cir.const #cir.int<63> : !u32i
+// CIR: cir.clz {{%.*}} poison_zero : !u64i
+// CIR: cir.cast integral {{%.*}} : !u64i -> !u32i
+// CIR: cir.sub nsw {{%.*}}, {{%.*}} : !u32i
+// CIR: cir.store align(4) {{%.*}}, {{%.*}} : !u32i, !cir.ptr<!u32i>
+// CIR: cir.cast bool_to_int [[NONZERO_REV64]] : !cir.bool -> !u8i
+#endif
+
+#ifdef __cplusplus
+}
+#endif
----------------
andykaylor wrote:

You're missing a newline at the end of the file.

https://github.com/llvm/llvm-project/pull/234304