spatel created this revision.
spatel added reviewers: fabiang, craig.topper, rnk, thakis.
Herald added a subscriber: mcrosier.
This exposes the LLVM funnel shift intrinsics as more familiar bit rotation
functions in clang (when both halves of a funnel shift are the same value, it's
a rotate).
I think we're free to name these as we want because we're not copying gcc, but
if there's some other existing art that we want to replicate, let me know.
The funnel shift intrinsics were added here:
https://reviews.llvm.org/D49242
With improved codegen in:
https://reviews.llvm.org/rL337966
https://reviews.llvm.org/rL339359
And basic IR optimization added in:
https://reviews.llvm.org/rL338218
https://reviews.llvm.org/rL340022
...so I think these should produce asm output that's equal or better to the
multi-instruction alternatives using primitive C/IR ops.
In the motivating loop example from PR37387:
https://bugs.llvm.org/show_bug.cgi?id=37387#c7
...we get the expected 'rolq' x86 instructions if we substitute the rotate
builtin into the source.
https://reviews.llvm.org/D50924
Files:
docs/LanguageExtensions.rst
include/clang/Basic/Builtins.def
lib/CodeGen/CGBuiltin.cpp
test/CodeGen/builtin-rotate.c
Index: test/CodeGen/builtin-rotate.c
===================================================================
--- test/CodeGen/builtin-rotate.c
+++ test/CodeGen/builtin-rotate.c
@@ -0,0 +1,66 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+
+unsigned char rotl8(unsigned char x, unsigned char y) {
+// CHECK-LABEL: rotl8
+// CHECK: [[F:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 [[Y:%.*]])
+// CHECK-NEXT: ret i8 [[F]]
+
+ return __builtin_rotateleft8(x, y);
+}
+
+short rotl16(short x, short y) {
+// CHECK-LABEL: rotl16
+// CHECK: [[F:%.*]] = call i16 @llvm.fshl.i16(i16 [[X:%.*]], i16 [[X]], i16 [[Y:%.*]])
+// CHECK-NEXT: ret i16 [[F]]
+
+ return __builtin_rotateleft16(x, y);
+}
+
+int rotl32(int x, unsigned int y) {
+// CHECK-LABEL: rotl32
+// CHECK: [[F:%.*]] = call i32 @llvm.fshl.i32(i32 [[X:%.*]], i32 [[X]], i32 [[Y:%.*]])
+// CHECK-NEXT: ret i32 [[F]]
+
+ return __builtin_rotateleft32(x, y);
+}
+
+unsigned long long rotl64(unsigned long long x, long long y) {
+// CHECK-LABEL: rotl64
+// CHECK: [[F:%.*]] = call i64 @llvm.fshl.i64(i64 [[X:%.*]], i64 [[X]], i64 [[Y:%.*]])
+// CHECK-NEXT: ret i64 [[F]]
+
+ return __builtin_rotateleft64(x, y);
+}
+
+char rotr8(char x, char y) {
+// CHECK-LABEL: rotr8
+// CHECK: [[F:%.*]] = call i8 @llvm.fshr.i8(i8 [[X:%.*]], i8 [[X]], i8 [[Y:%.*]])
+// CHECK-NEXT: ret i8 [[F]]
+
+ return __builtin_rotateright8(x, y);
+}
+
+unsigned short rotr16(unsigned short x, unsigned short y) {
+// CHECK-LABEL: rotr16
+// CHECK: [[F:%.*]] = call i16 @llvm.fshr.i16(i16 [[X:%.*]], i16 [[X]], i16 [[Y:%.*]])
+// CHECK-NEXT: ret i16 [[F]]
+
+ return __builtin_rotateright16(x, y);
+}
+
+unsigned int rotr32(unsigned int x, int y) {
+// CHECK-LABEL: rotr32
+// CHECK: [[F:%.*]] = call i32 @llvm.fshr.i32(i32 [[X:%.*]], i32 [[X]], i32 [[Y:%.*]])
+// CHECK-NEXT: ret i32 [[F]]
+
+ return __builtin_rotateright32(x, y);
+}
+
+long long rotr64(long long x, unsigned long long y) {
+// CHECK-LABEL: rotr64
+// CHECK: [[F:%.*]] = call i64 @llvm.fshr.i64(i64 [[X:%.*]], i64 [[X]], i64 [[Y:%.*]])
+// CHECK-NEXT: ret i64 [[F]]
+
+ return __builtin_rotateright64(x, y);
+}
+
Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -1741,6 +1741,25 @@
case Builtin::BI__builtin_bitreverse64: {
return RValue::get(emitUnaryBuiltin(*this, E, Intrinsic::bitreverse));
}
+ case Builtin::BI__builtin_rotateleft8:
+ case Builtin::BI__builtin_rotateleft16:
+ case Builtin::BI__builtin_rotateleft32:
+ case Builtin::BI__builtin_rotateleft64: {
+ llvm::Value *Src = EmitScalarExpr(E->getArg(0));
+ llvm::Value *ShiftAmt = EmitScalarExpr(E->getArg(1));
+ Value *F = CGM.getIntrinsic(Intrinsic::fshl, Src->getType());
+ return RValue::get(Builder.CreateCall(F, { Src, Src, ShiftAmt }));
+ }
+ case Builtin::BI__builtin_rotateright8:
+ case Builtin::BI__builtin_rotateright16:
+ case Builtin::BI__builtin_rotateright32:
+ case Builtin::BI__builtin_rotateright64: {
+ llvm::Value *Src = EmitScalarExpr(E->getArg(0));
+ llvm::Value *ShiftAmt = EmitScalarExpr(E->getArg(1));
+ Value *F = CGM.getIntrinsic(Intrinsic::fshr, Src->getType());
+ return RValue::get(Builder.CreateCall(F, { Src, Src, ShiftAmt }));
+ }
+
case Builtin::BI__builtin_object_size: {
unsigned Type =
E->getArg(1)->EvaluateKnownConstInt(getContext()).getZExtValue();
Index: include/clang/Basic/Builtins.def
===================================================================
--- include/clang/Basic/Builtins.def
+++ include/clang/Basic/Builtins.def
@@ -428,6 +428,15 @@
BUILTIN(__builtin_bitreverse32, "UiUi", "nc")
BUILTIN(__builtin_bitreverse64, "ULLiULLi", "nc")
+BUILTIN(__builtin_rotateleft8, "UcUcUc", "nc")
+BUILTIN(__builtin_rotateleft16, "UsUsUs", "nc")
+BUILTIN(__builtin_rotateleft32, "UiUiUi", "nc")
+BUILTIN(__builtin_rotateleft64, "ULLiULLiULLi", "nc")
+BUILTIN(__builtin_rotateright8, "UcUcUc", "nc")
+BUILTIN(__builtin_rotateright16, "UsUsUs", "nc")
+BUILTIN(__builtin_rotateright32, "UiUiUi", "nc")
+BUILTIN(__builtin_rotateright64, "ULLiULLiULLi", "nc")
+
// Random GCC builtins
BUILTIN(__builtin_constant_p, "i.", "nctu")
BUILTIN(__builtin_classify_type, "i.", "nctu")
Index: docs/LanguageExtensions.rst
===================================================================
--- docs/LanguageExtensions.rst
+++ docs/LanguageExtensions.rst
@@ -1739,6 +1739,70 @@
the bitpattern of an integer value; for example ``0b10110110`` becomes
``0b01101101``.
+``__builtin_rotateleft``
+------------------------
+
+* ``__builtin_rotateleft8``
+* ``__builtin_rotateleft16``
+* ``__builtin_rotateleft32``
+* ``__builtin_rotateleft64``
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_rotateleft32(x, y)
+
+**Examples**:
+
+.. code-block:: c++
+
+ uint8_t rot_x = __builtin_rotateleft8(x, y);
+ uint16_t rot_x = __builtin_rotateleft16(x, y);
+ uint32_t rot_x = __builtin_rotateleft32(x, y);
+ uint64_t rot_x = __builtin_rotateleft64(x, y);
+
+**Description**:
+
+The '``__builtin_rotateleft``' family of builtins is used to rotate
+the bits in the first argument by the amount in the second argument.
+For example, ``0b10000110`` rotated left by 11 becomes ``0b00110100``.
+The shift value is treated as an unsigned amount modulo the size of
+the arguments. Both arguments and the result have the bitwidth specified
+by the name of the builtin.
+
+``__builtin_rotateright``
+------------------------
+
+* ``__builtin_rotaterigh8``
+* ``__builtin_rotateright16``
+* ``__builtin_rotateright32``
+* ``__builtin_rotateright64``
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_rotateright32(x, y)
+
+**Examples**:
+
+.. code-block:: c++
+
+ uint8_t rot_x = __builtin_rotateright8(x, y);
+ uint16_t rot_x = __builtin_rotateright16(x, y);
+ uint32_t rot_x = __builtin_rotateright32(x, y);
+ uint64_t rot_x = __builtin_rotateright64(x, y);
+
+**Description**:
+
+The '``__builtin_rotateright``' family of builtins is used to rotate
+the bits in the first argument by the amount in the second argument.
+For example, ``0b10000110`` rotated right by 3 becomes ``0b11010000``.
+The shift value is treated as an unsigned amount modulo the size of
+the arguments. Both arguments and the result have the bitwidth specified
+by the name of the builtin.
+
``__builtin_unreachable``
-------------------------
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