1 ; RUN: opt < %s -instcombine -S -data-layout=e-n32 | FileCheck %s --check-prefix=ALL --check-prefix=LE 2 ; RUN: opt < %s -instcombine -S -data-layout=E-n32 | FileCheck %s --check-prefix=ALL --check-prefix=BE 3 4 declare i32 @memcmp(i8*, i8*, i64) 5 6 ; The alignment of this constant does not matter. We constant fold the load. 7 8 @charbuf = private unnamed_addr constant [4 x i8] [i8 0, i8 0, i8 0, i8 1], align 1 9 10 define i1 @memcmp_4bytes_unaligned_constant_i8(i8* align 4 %x) { 11 ; LE-LABEL: @memcmp_4bytes_unaligned_constant_i8( 12 ; LE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32* 13 ; LE-NEXT: [[LHSV:%.*]] = load i32, i32* [[TMP1]], align 4 14 ; LE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[LHSV]], 16777216 15 ; LE-NEXT: ret i1 [[TMP2]] 16 ; 17 ; BE-LABEL: @memcmp_4bytes_unaligned_constant_i8( 18 ; BE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32* 19 ; BE-NEXT: [[LHSV:%.*]] = load i32, i32* [[TMP1]], align 4 20 ; BE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[LHSV]], 1 21 ; BE-NEXT: ret i1 [[TMP2]] 22 ; 23 %call = tail call i32 @memcmp(i8* %x, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @charbuf, i64 0, i64 0), i64 4) 24 %cmpeq0 = icmp eq i32 %call, 0 25 ret i1 %cmpeq0 26 } 27 28 ; We still don't care about alignment of the constant. We are not limited to constant folding only i8 arrays. 29 ; It doesn't matter if the constant operand is the first operand to the memcmp. 30 31 @intbuf_unaligned = private unnamed_addr constant [4 x i16] [i16 1, i16 2, i16 3, i16 4], align 1 32 33 define i1 @memcmp_4bytes_unaligned_constant_i16(i8* align 4 %x) { 34 ; LE-LABEL: @memcmp_4bytes_unaligned_constant_i16( 35 ; LE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32* 36 ; LE-NEXT: [[RHSV:%.*]] = load i32, i32* [[TMP1]], align 4 37 ; LE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[RHSV]], 131073 38 ; LE-NEXT: ret i1 [[TMP2]] 39 ; 40 ; BE-LABEL: @memcmp_4bytes_unaligned_constant_i16( 41 ; BE-NEXT: [[TMP1:%.*]] = bitcast i8* %x to i32* 42 ; BE-NEXT: [[RHSV:%.*]] = load i32, i32* [[TMP1]], align 4 43 ; BE-NEXT: [[TMP2:%.*]] = icmp eq i32 [[RHSV]], 65538 44 ; BE-NEXT: ret i1 [[TMP2]] 45 ; 46 %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) 47 %cmpeq0 = icmp eq i32 %call, 0 48 ret i1 %cmpeq0 49 } 50 51 ; TODO: Any memcmp where all arguments are constants should be constant folded. Currently, we only handle i8 array constants. 52 53 @intbuf = private unnamed_addr constant [2 x i32] [i32 0, i32 1], align 4 54 55 define i1 @memcmp_3bytes_aligned_constant_i32(i8* align 4 %x) { 56 ; ALL-LABEL: @memcmp_3bytes_aligned_constant_i32( 57 ; 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) 58 ; ALL-NEXT: [[CMPEQ0:%.*]] = icmp eq i32 [[CALL]], 0 59 ; ALL-NEXT: ret i1 [[CMPEQ0]] 60 ; 61 %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) 62 %cmpeq0 = icmp eq i32 %call, 0 63 ret i1 %cmpeq0 64 } 65 66 ; A sloppy implementation would infinite loop by recreating the unused instructions. 67 68 define i1 @memcmp_4bytes_one_unaligned_i8(i8* align 4 %x, i8* align 1 %y) { 69 ; ALL-LABEL: @memcmp_4bytes_one_unaligned_i8( 70 ; ALL-NEXT: [[CALL:%.*]] = tail call i32 @memcmp(i8* %x, i8* %y, i64 4) 71 ; ALL-NEXT: [[CMPEQ0:%.*]] = icmp eq i32 [[CALL]], 0 72 ; ALL-NEXT: ret i1 [[CMPEQ0]] 73 ; 74 %bc = bitcast i8* %x to i32* 75 %lhsv = load i32, i32* %bc 76 %call = tail call i32 @memcmp(i8* %x, i8* %y, i64 4) 77 %cmpeq0 = icmp eq i32 %call, 0 78 ret i1 %cmpeq0 79 } 80 81
