9ad72df55c
There are two problems with _BitInt prior to this patch:
1. For at least some values of N, we cannot use LLVM's iN for the type
of struct elements, array elements, allocas, global variables, and so
on, because the LLVM layout for that type does not match the high-level
layout of _BitInt(N).
Example: Currently for i128:128 targets correct implementation is
possible either for __int128 or for _BitInt(129+) with lowering to iN,
but not both, since we have now correct implementation of __int128 in
place after a21abc7.
When this happens, opaque [M x i8] types used, where M =
sizeof(_BitInt(N)).
2. LLVM doesn't guarantee any particular extension behavior for integer
types that aren't a multiple of 8. For this reason, all _BitInt types
are now have in-memory representation that is a whole number of bytes.
I.e. for example _BitInt(17) now will have memory layout type i32.
This patch also introduces concept of load/store type and adds an API to
CodeGenTypes that returns the IR type that should be used for load and
store operations. This is particularly useful for the case when a
_BitInt ends up having array of bytes as memory layout type. For
_BitInt(N), let M = sizeof(_BitInt(N)), and let BITS = M * 8. Loads and
stores of iM would both (1) produce far better code from the backends
and (2) be far more optimizable by IR passes than loads and stores of [M
x i8].
Fixes https://github.com/llvm/llvm-project/issues/85139
Fixes https://github.com/llvm/llvm-project/issues/83419
---------
Co-authored-by: John McCall <rjmccall@gmail.com>
121 lines
6.7 KiB
C
121 lines
6.7 KiB
C
// RUN: %clang_cc1 -emit-llvm -triple arm64-- -fexperimental-max-bitint-width=1024 -o - %s -O0 | FileCheck %s --check-prefix=CHECK-O0
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// RUN: %clang_cc1 -emit-llvm -disable-llvm-optzns -fexperimental-max-bitint-width=1024 -triple arm64-- -o - %s -O3 | FileCheck %s --check-prefix=CHECK-O3
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struct large {
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void* pointers[8];
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};
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void pass_large(struct large);
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void pass_large_BitInt(_BitInt(129));
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// For arm64, we don't use byval to pass structs and _BitInt(>128) type, but instead we create
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// temporary allocas.
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//
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// Make sure we generate the appropriate lifetime markers for the temporary
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// allocas so that the optimizer can re-use stack slots if possible.
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void example(void) {
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struct large l = {0};
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pass_large(l);
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pass_large(l);
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}
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// CHECK-O0-LABEL: define{{.*}} void @example(
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// The alloca for the struct on the stack.
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// CHECK-O0: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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// The alloca for the temporary stack space that we use to pass the argument.
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// CHECK-O0-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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// Another one to pass the argument to the second function call.
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// CHECK-O0-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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// First, memset `l` to 0.
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// CHECK-O0-NEXT: call void @llvm.memset.p0.i64(ptr align 8 %[[l]], i8 0, i64 64, i1 false)
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// Then, memcpy `l` to the temporary stack space.
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// CHECK-O0-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 8 %[[byvaltemp]], ptr align 8 %[[l]], i64 64, i1 false)
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// Finally, call using a pointer to the temporary stack space.
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// CHECK-O0-NEXT: call void @pass_large(ptr noundef %[[byvaltemp]])
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// Now, do the same for the second call, using the second temporary alloca.
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// CHECK-O0-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 8 %[[byvaltemp1]], ptr align 8 %[[l]], i64 64, i1 false)
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// CHECK-O0-NEXT: call void @pass_large(ptr noundef %[[byvaltemp1]])
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// CHECK-O0-NEXT: ret void
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//
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// At O3, we should have lifetime markers to help the optimizer re-use the temporary allocas.
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//
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// CHECK-O3-LABEL: define{{.*}} void @example(
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// The alloca for the struct on the stack.
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// CHECK-O3: %[[l:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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// The alloca for the temporary stack space that we use to pass the argument.
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// CHECK-O3-NEXT: %[[byvaltemp:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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// Another one to pass the argument to the second function call.
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// CHECK-O3-NEXT: %[[byvaltemp1:[0-9A-Za-z-]+]] = alloca %struct.large, align 8
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//
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// Mark the start of the lifetime for `l`
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 64, ptr %[[l]])
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//
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// First, memset `l` to 0.
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// CHECK-O3-NEXT: call void @llvm.memset.p0.i64(ptr align 8 %[[l]], i8 0, i64 64, i1 false)
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//
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// Lifetime of the first temporary starts here and ends right after the call.
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 64, ptr %[[byvaltemp]])
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//
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// Then, memcpy `l` to the temporary stack space.
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// CHECK-O3-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 8 %[[byvaltemp]], ptr align 8 %[[l]], i64 64, i1 false)
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// Finally, call using a pointer to the temporary stack space.
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// CHECK-O3-NEXT: call void @pass_large(ptr noundef %[[byvaltemp]])
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//
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// The lifetime of the temporary used to pass a pointer to the struct ends here.
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 64, ptr %[[byvaltemp]])
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//
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// Now, do the same for the second call, using the second temporary alloca.
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 64, ptr %[[byvaltemp1]])
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// CHECK-O3-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 8 %[[byvaltemp1]], ptr align 8 %[[l]], i64 64, i1 false)
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// CHECK-O3-NEXT: call void @pass_large(ptr noundef %[[byvaltemp1]])
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 64, ptr %[[byvaltemp1]])
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//
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// Mark the end of the lifetime of `l`.
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 64, ptr %l)
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// CHECK-O3-NEXT: ret void
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void example_BitInt(void) {
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_BitInt(129) l = {0};
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pass_large_BitInt(l);
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pass_large_BitInt(l);
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}
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// CHECK-O0-LABEL: define dso_local void @example_BitInt(
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// CHECK-O0-NEXT: entry:
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// CHECK-O0-NEXT: [[L:%.*]] = alloca i256, align 16
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// CHECK-O0-NEXT: [[INDIRECT_ARG_TEMP:%.*]] = alloca i256, align 16
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// CHECK-O0-NEXT: [[INDIRECT_ARG_TEMP1:%.*]] = alloca i256, align 16
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// CHECK-O0-NEXT: store i256 0, ptr [[L]], align 16
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// CHECK-O0-NEXT: [[TMP0:%.*]] = load i256, ptr [[L]], align 16
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// CHECK-O0-NEXT: [[LOADEDV:%.*]] = trunc i256 [[TMP0]] to i129
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// CHECK-O0-NEXT: [[STOREDV:%.*]] = sext i129 [[LOADEDV]] to i256
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// CHECK-O0-NEXT: store i256 [[STOREDV]], ptr [[INDIRECT_ARG_TEMP]], align 16
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// CHECK-O0-NEXT: call void @pass_large_BitInt(ptr noundef [[INDIRECT_ARG_TEMP]])
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// CHECK-O0-NEXT: [[TMP1:%.*]] = load i256, ptr [[L]], align 16
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// CHECK-O0-NEXT: [[LOADEDV1:%.*]] = trunc i256 [[TMP1]] to i129
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// CHECK-O0-NEXT: [[STOREDV1:%.*]] = sext i129 [[LOADEDV1]] to i256
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// CHECK-O0-NEXT: store i256 [[STOREDV1]], ptr [[INDIRECT_ARG_TEMP1]], align 16
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// CHECK-O0-NEXT: call void @pass_large_BitInt(ptr noundef [[INDIRECT_ARG_TEMP1]])
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// CHECK-O0-NEXT: ret void
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//
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// CHECK-O3-LABEL: define dso_local void @example_BitInt(
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// CHECK-O3-NEXT: entry:
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// CHECK-O3-NEXT: [[L:%.*]] = alloca i256, align 16
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// CHECK-O3-NEXT: [[INDIRECT_ARG_TEMP:%.*]] = alloca i256, align 16
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// CHECK-O3-NEXT: [[INDIRECT_ARG_TEMP1:%.*]] = alloca i256, align 16
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 32, ptr [[L]])
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// CHECK-O3-NEXT: store i256 0, ptr [[L]], align 16, !tbaa [[TBAA6:![0-9]+]]
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// CHECK-O3-NEXT: [[TMP0:%.*]] = load i256, ptr [[L]], align 16, !tbaa [[TBAA6]]
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// CHECK-O3-NEXT: [[LOADEDV:%.*]] = trunc i256 [[TMP0]] to i129
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 32, ptr [[INDIRECT_ARG_TEMP]])
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// CHECK-O3-NEXT: [[STOREDV:%.*]] = sext i129 [[LOADEDV]] to i256
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// CHECK-O3-NEXT: store i256 [[STOREDV]], ptr [[INDIRECT_ARG_TEMP]], align 16, !tbaa [[TBAA6]]
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// CHECK-O3-NEXT: call void @pass_large_BitInt(ptr noundef [[INDIRECT_ARG_TEMP]])
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 32, ptr [[INDIRECT_ARG_TEMP]])
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// CHECK-O3-NEXT: [[TMP1:%.*]] = load i256, ptr [[L]], align 16, !tbaa [[TBAA6]]
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// CHECK-O3-NEXT: [[LOADEDV1:%.*]] = trunc i256 [[TMP1]] to i129
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// CHECK-O3-NEXT: call void @llvm.lifetime.start.p0(i64 32, ptr [[INDIRECT_ARG_TEMP1]])
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// CHECK-O3-NEXT: [[STOREDV1:%.*]] = sext i129 [[LOADEDV1]] to i256
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// CHECK-O3-NEXT: store i256 [[STOREDV1]], ptr [[INDIRECT_ARG_TEMP1]], align 16, !tbaa [[TBAA6]]
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// CHECK-O3-NEXT: call void @pass_large_BitInt(ptr noundef [[INDIRECT_ARG_TEMP1]])
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 32, ptr [[INDIRECT_ARG_TEMP1]])
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// CHECK-O3-NEXT: call void @llvm.lifetime.end.p0(i64 32, ptr [[L]])
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