78de7297ab
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html Complemantary to the assumption outliner prototype in D71692, this patch shows how we could simplify the code emitted for an alignemnt assumption. The generated code is smaller, less fragile, and it makes it easier to recognize the additional use as a "assumption use". As mentioned in D71692 and on the mailing list, we could adopt this scheme, and similar schemes for other patterns, without adopting the assumption outlining.
67 lines
3.9 KiB
C
67 lines
3.9 KiB
C
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
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/// Check that the alignment builtins handle array-to-pointer decay
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// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -o - -emit-llvm %s | FileCheck %s
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extern int func(char *c);
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// CHECK-LABEL: @test_array(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: [[BUF:%.*]] = alloca [1024 x i8], align 16
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// CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [1024 x i8], [1024 x i8]* [[BUF]], i64 0, i64 44
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// CHECK-NEXT: [[INTPTR:%.*]] = ptrtoint i8* [[ARRAYIDX]] to i64
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// CHECK-NEXT: [[ALIGNED_INTPTR:%.*]] = and i64 [[INTPTR]], -16
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// CHECK-NEXT: [[DIFF:%.*]] = sub i64 [[ALIGNED_INTPTR]], [[INTPTR]]
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// CHECK-NEXT: [[ALIGNED_RESULT:%.*]] = getelementptr inbounds i8, i8* [[ARRAYIDX]], i64 [[DIFF]]
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// CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[ALIGNED_RESULT]], i64 16) ]
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// CHECK-NEXT: [[CALL:%.*]] = call i32 @func(i8* [[ALIGNED_RESULT]])
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// CHECK-NEXT: [[ARRAYIDX1:%.*]] = getelementptr inbounds [1024 x i8], [1024 x i8]* [[BUF]], i64 0, i64 22
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// CHECK-NEXT: [[INTPTR2:%.*]] = ptrtoint i8* [[ARRAYIDX1]] to i64
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// CHECK-NEXT: [[OVER_BOUNDARY:%.*]] = add i64 [[INTPTR2]], 31
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// CHECK-NEXT: [[ALIGNED_INTPTR4:%.*]] = and i64 [[OVER_BOUNDARY]], -32
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// CHECK-NEXT: [[DIFF5:%.*]] = sub i64 [[ALIGNED_INTPTR4]], [[INTPTR2]]
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// CHECK-NEXT: [[ALIGNED_RESULT6:%.*]] = getelementptr inbounds i8, i8* [[ARRAYIDX1]], i64 [[DIFF5]]
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// CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[ALIGNED_RESULT6]], i64 32) ]
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// CHECK-NEXT: [[CALL7:%.*]] = call i32 @func(i8* [[ALIGNED_RESULT6]])
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// CHECK-NEXT: [[ARRAYIDX8:%.*]] = getelementptr inbounds [1024 x i8], [1024 x i8]* [[BUF]], i64 0, i64 16
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// CHECK-NEXT: [[SRC_ADDR:%.*]] = ptrtoint i8* [[ARRAYIDX8]] to i64
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// CHECK-NEXT: [[SET_BITS:%.*]] = and i64 [[SRC_ADDR]], 63
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// CHECK-NEXT: [[IS_ALIGNED:%.*]] = icmp eq i64 [[SET_BITS]], 0
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// CHECK-NEXT: [[CONV:%.*]] = zext i1 [[IS_ALIGNED]] to i32
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// CHECK-NEXT: ret i32 [[CONV]]
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//
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int test_array(void) {
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char buf[1024];
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func(__builtin_align_down(&buf[44], 16));
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func(__builtin_align_up(&buf[22], 32));
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return __builtin_is_aligned(&buf[16], 64);
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}
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// CHECK-LABEL: @test_array_should_not_mask(
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// CHECK-NEXT: entry:
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// CHECK-NEXT: [[BUF:%.*]] = alloca [1024 x i8], align 32
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// CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds [1024 x i8], [1024 x i8]* [[BUF]], i64 0, i64 64
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// CHECK-NEXT: [[INTPTR:%.*]] = ptrtoint i8* [[ARRAYIDX]] to i64
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// CHECK-NEXT: [[ALIGNED_INTPTR:%.*]] = and i64 [[INTPTR]], -16
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// CHECK-NEXT: [[DIFF:%.*]] = sub i64 [[ALIGNED_INTPTR]], [[INTPTR]]
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// CHECK-NEXT: [[ALIGNED_RESULT:%.*]] = getelementptr inbounds i8, i8* [[ARRAYIDX]], i64 [[DIFF]]
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// CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[ALIGNED_RESULT]], i64 16) ]
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// CHECK-NEXT: [[CALL:%.*]] = call i32 @func(i8* [[ALIGNED_RESULT]])
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// CHECK-NEXT: [[ARRAYIDX1:%.*]] = getelementptr inbounds [1024 x i8], [1024 x i8]* [[BUF]], i64 0, i64 32
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// CHECK-NEXT: [[INTPTR2:%.*]] = ptrtoint i8* [[ARRAYIDX1]] to i64
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// CHECK-NEXT: [[OVER_BOUNDARY:%.*]] = add i64 [[INTPTR2]], 31
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// CHECK-NEXT: [[ALIGNED_INTPTR4:%.*]] = and i64 [[OVER_BOUNDARY]], -32
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// CHECK-NEXT: [[DIFF5:%.*]] = sub i64 [[ALIGNED_INTPTR4]], [[INTPTR2]]
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// CHECK-NEXT: [[ALIGNED_RESULT6:%.*]] = getelementptr inbounds i8, i8* [[ARRAYIDX1]], i64 [[DIFF5]]
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// CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* [[ALIGNED_RESULT6]], i64 32) ]
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// CHECK-NEXT: [[CALL7:%.*]] = call i32 @func(i8* [[ALIGNED_RESULT6]])
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// CHECK-NEXT: ret i32 1
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//
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int test_array_should_not_mask(void) {
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_Alignas(32) char buf[1024];
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// TODO: The align_up and align_down calls should be folded to no-ops
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func(__builtin_align_down(&buf[64], 16));
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func(__builtin_align_up(&buf[32], 32));
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// This expression can be constant-evaluated:
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return __builtin_is_aligned(&buf[64], 32);
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}
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