[PATCH] D75723: [X86] Enable intrinsics _BitScan*

[Kan Shengchen via Phabricator via cfe-commits]

skan updated this revision to Diff 249282.
skan added a comment.

Enable _BitScan* as intrinsics rather than builtin on linux


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75723/new/

https://reviews.llvm.org/D75723

Files:
  clang/lib/Headers/ia32intrin.h
  clang/test/CodeGen/bitscan-builtins.c


Index: clang/test/CodeGen/bitscan-builtins.c
===================================================================
--- clang/test/CodeGen/bitscan-builtins.c
+++ clang/test/CodeGen/bitscan-builtins.c
@@ -5,6 +5,32 @@
 
 #include <x86intrin.h>
 
+unsigned char test_BitScanForward(unsigned *index, unsigned mask) {
+  return _BitScanForward(index, mask);
+  // CHECK: @test_BitScanForward
+  // CHECK: %{{.*}} = call i32 @llvm.cttz.i32(i32 %{{.*}}, i1 true)
+}
+
+unsigned char test_BitScanReverse(unsigned *index, unsigned mask) {
+  return _BitScanReverse(index, mask);
+  // CHECK: @test_BitScanReverse
+  // CHECK:  %[[call:.*]] = call i32 @llvm.ctlz.i32(i32 %{{.*}}, i1 true)
+  // CHECK:  %{{.*}} = sub nsw i32 31, %[[call]]
+}
+
+unsigned char test_BitScanForward64(unsigned *index, unsigned long long mask) {
+  return _BitScanForward64(index, mask);
+  // CHECK: @test_BitScanForward64
+  // CHECK: %{{.*}} = call i64 @llvm.cttz.i64(i64 %{{.*}}, i1 true)
+}
+
+unsigned char test_BitScanReverse64(unsigned *index, unsigned long long mask) {
+  return _BitScanReverse64(index, mask);
+  // CHECK: @test_BitScanReverse64
+  // CHECK:  %{{.*}} = call i64 @llvm.ctlz.i64(i64 %{{.*}}, i1 true)
+  // CHECK:  %{{.*}} = sub nsw i32 63, %{{.*}}
+}
+
 int test_bit_scan_forward(int a) {
   return _bit_scan_forward(a);
 // CHECK: @test_bit_scan_forward
Index: clang/lib/Headers/ia32intrin.h
===================================================================
--- clang/lib/Headers/ia32intrin.h
+++ clang/lib/Headers/ia32intrin.h
@@ -413,6 +413,26 @@
 
 #ifndef _MSC_VER
 /* These are already provided as builtins for MSVC. */
+#define _BitScanForward(a, b)                                                  \
+  __extension__({                                                              \
+    *(a) = (unsigned)__bsfd((int)(b));                                         \
+    (unsigned char)((b) != 0);                                                 \
+  })
+#define _BitScanReverse(a, b)                                                  \
+  __extension__({                                                              \
+    *(a) = (unsigned)__bsrd((int)(b));                                         \
+    (unsigned char)((b) != 0);                                                 \
+  })
+#define _BitScanForward64(a, b)                                                \
+  __extension__({                                                              \
+    *(a) = (unsigned)__bsfq((long long)(b));                                   \
+    (unsigned char)((b) != 0);                                                 \
+  })
+#define _BitScanReverse64(a, b)                                                \
+  __extension__({                                                              \
+    *(a) = (unsigned)__bsrq((long long)(b));                                   \
+    (unsigned char)((b) != 0);                                                 \
+  })
 /* Select the correct function based on the size of long. */
 #ifdef __LP64__
 #define _lrotl(a,b) __rolq((a), (b))


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