forked from OSchip/llvm-project
81 lines
3.6 KiB
LLVM
81 lines
3.6 KiB
LLVM
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; RUN: opt < %s -instcombine -S -data-layout=e-n32 | FileCheck %s --check-prefix=ALL --check-prefix=LE
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; RUN: opt < %s -instcombine -S -data-layout=E-n32 | FileCheck %s --check-prefix=ALL --check-prefix=BE
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declare i32 @memcmp(i8*, i8*, i64)
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; The alignment of this constant does not matter. We constant fold the load.
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@charbuf = private unnamed_addr constant [4 x i8] [i8 0, i8 0, i8 0, i8 1], align 1
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define i1 @memcmp_4bytes_unaligned_constant_i8(i8* align 4 %x) {
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; LE-LABEL: @memcmp_4bytes_unaligned_constant_i8(
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; LE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32*
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; LE-NEXT: [[LHSV:%.*]] = load i32, i32* [[TMP1]], align 4
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; LE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[LHSV]], 16777216
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; LE-NEXT: ret i1 [[TMP2]]
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;
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; BE-LABEL: @memcmp_4bytes_unaligned_constant_i8(
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; BE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32*
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; BE-NEXT: [[LHSV:%.*]] = load i32, i32* [[TMP1]], align 4
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; BE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[LHSV]], 1
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; BE-NEXT: ret i1 [[TMP2]]
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;
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%call = tail call i32 @memcmp(i8* %x, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @charbuf, i64 0, i64 0), i64 4)
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%cmpeq0 = icmp eq i32 %call, 0
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ret i1 %cmpeq0
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}
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; We still don't care about alignment of the constant. We are not limited to constant folding only i8 arrays.
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; It doesn't matter if the constant operand is the first operand to the memcmp.
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@intbuf_unaligned = private unnamed_addr constant [4 x i16] [i16 1, i16 2, i16 3, i16 4], align 1
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define i1 @memcmp_4bytes_unaligned_constant_i16(i8* align 4 %x) {
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; LE-LABEL: @memcmp_4bytes_unaligned_constant_i16(
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; LE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32*
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; LE-NEXT: [[RHSV:%.*]] = load i32, i32* [[TMP1]], align 4
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; LE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[RHSV]], 131073
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; LE-NEXT: ret i1 [[TMP2]]
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;
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; BE-LABEL: @memcmp_4bytes_unaligned_constant_i16(
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; BE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32*
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; BE-NEXT: [[RHSV:%.*]] = load i32, i32* [[TMP1]], align 4
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; BE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[RHSV]], 65538
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; BE-NEXT: ret i1 [[TMP2]]
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;
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%call = tail call i32 @memcmp(i8* bitcast (i16* getelementptr inbounds ([4 x i16], [4 x i16]* @intbuf_unaligned, i64 0, i64 0) to i8*), i8* %x, i64 4)
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%cmpeq0 = icmp eq i32 %call, 0
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ret i1 %cmpeq0
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}
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; TODO: Any memcmp where all arguments are constants should be constant folded. Currently, we only handle i8 array constants.
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@intbuf = private unnamed_addr constant [2 x i32] [i32 0, i32 1], align 4
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define i1 @memcmp_3bytes_aligned_constant_i32(i8* align 4 %x) {
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; ALL-LABEL: @memcmp_3bytes_aligned_constant_i32(
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; ALL-NEXT: [[CALL:%.*]] = tail call i32 @memcmp(i8* bitcast (i32* getelementptr inbounds ([2 x i32], [2 x i32]* @intbuf, i64 0, i64 1) to i8*), i8* bitcast ([2 x i32]* @intbuf to i8*), i64 3)
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; ALL-NEXT: [[CMPEQ0:%.*]] = icmp eq i32 [[CALL]], 0
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; ALL-NEXT: ret i1 [[CMPEQ0]]
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;
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%call = tail call i32 @memcmp(i8* bitcast (i32* getelementptr inbounds ([2 x i32], [2 x i32]* @intbuf, i64 0, i64 1) to i8*), i8* bitcast (i32* getelementptr inbounds ([2 x i32], [2 x i32]* @intbuf, i64 0, i64 0) to i8*), i64 3)
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%cmpeq0 = icmp eq i32 %call, 0
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ret i1 %cmpeq0
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}
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; A sloppy implementation would infinite loop by recreating the unused instructions.
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define i1 @memcmp_4bytes_one_unaligned_i8(i8* align 4 %x, i8* align 1 %y) {
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; ALL-LABEL: @memcmp_4bytes_one_unaligned_i8(
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; ALL-NEXT: [[CALL:%.*]] = tail call i32 @memcmp(i8* %x, i8* %y, i64 4)
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; ALL-NEXT: [[CMPEQ0:%.*]] = icmp eq i32 [[CALL]], 0
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; ALL-NEXT: ret i1 [[CMPEQ0]]
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;
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%bc = bitcast i8* %x to i32*
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%lhsv = load i32, i32* %bc
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%call = tail call i32 @memcmp(i8* %x, i8* %y, i64 4)
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%cmpeq0 = icmp eq i32 %call, 0
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ret i1 %cmpeq0
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}
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