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>
70 lines
2.7 KiB
C
70 lines
2.7 KiB
C
// RUN: %clang_cc1 %s -O0 -fsanitize=shift-exponent -emit-llvm -std=c2x -triple=x86_64-unknown-linux -o - | FileCheck %s
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// Checking that the code generation is using the unextended/untruncated
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// exponent values and capping the values accordingly
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// CHECK-LABEL: define{{.*}} i32 @test_left_variable
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int test_left_variable(unsigned _BitInt(5) b, unsigned _BitInt(2) e) {
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// CHECK: load i8
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// CHECK: [[E_REG:%.+]] = trunc i8 {{.*}} to [[E_SIZE:i2]]
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// CHECK: icmp ule [[E_SIZE]] [[E_REG]], -1,
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return b << e;
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}
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// CHECK-LABEL: define{{.*}} i32 @test_right_variable
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int test_right_variable(unsigned _BitInt(2) b, unsigned _BitInt(3) e) {
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// CHECK: load i8
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// CHECK: [[E_REG:%.+]] = trunc i8 {{.*}} to [[E_SIZE:i3]]
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// CHECK: icmp ule [[E_SIZE]] [[E_REG]], 1,
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return b >> e;
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}
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// Old code generation would give false positives on left shifts when:
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// value(e) > (width(b) - 1 % 2 ** width(e))
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// CHECK-LABEL: define{{.*}} i32 @test_left_literal
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int test_left_literal(unsigned _BitInt(5) b) {
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// CHECK-NOT: br i1 false, label %cont, label %handler.shift_out_of_bounds
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// CHECK: br i1 true, label %cont, label %handler.shift_out_of_bounds
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return b << 3uwb;
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}
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// Old code generation would give false positives on right shifts when:
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// (value(e) % 2 ** width(b)) < width(b)
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// CHECK-LABEL: define{{.*}} i32 @test_right_literal
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int test_right_literal(unsigned _BitInt(2) b) {
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// CHECK-NOT: br i1 true, label %cont, label %handler.shift_out_of_bounds
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// CHECK: br i1 false, label %cont, label %handler.shift_out_of_bounds
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return b >> 4uwb;
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}
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// CHECK-LABEL: define{{.*}} i32 @test_signed_left_variable
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int test_signed_left_variable(unsigned _BitInt(15) b, _BitInt(2) e) {
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// CHECK: load i8
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// CHECK: [[E_REG:%.+]] = trunc i8 {{.*}} to [[E_SIZE:i2]]
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// CHECK: icmp ule [[E_SIZE]] [[E_REG]], 1,
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return b << e;
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}
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// CHECK-LABEL: define{{.*}} i32 @test_signed_right_variable
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int test_signed_right_variable(unsigned _BitInt(32) b, _BitInt(4) e) {
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// CHECK: load i8
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// CHECK: [[E_REG:%.+]] = trunc i8 {{.*}} to [[E_SIZE:i4]]
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// CHECK: icmp ule [[E_SIZE]] [[E_REG]], 7,
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return b >> e;
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}
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// CHECK-LABEL: define{{.*}} i32 @test_signed_left_literal
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int test_signed_left_literal(unsigned _BitInt(16) b) {
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// CHECK-NOT: br i1 true, label %cont, label %handler.shift_out_of_bounds
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// CHECK: br i1 false, label %cont, label %handler.shift_out_of_bounds
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return b << (_BitInt(4))-2wb;
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}
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// CHECK-LABEL: define{{.*}} i32 @test_signed_right_literal
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int test_signed_right_literal(unsigned _BitInt(16) b) {
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// CHECK-NOT: br i1 true, label %cont, label %handler.shift_out_of_bounds
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// CHECK: br i1 false, label %cont, label %handler.shift_out_of_bounds
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return b >> (_BitInt(4))-8wb;
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}
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