; bswap should be constant folded when it is passed a constant argument
-; RUN: llvm-upgrade < %s | llvm-as | llc -march=x86 | grep bswapl | wc -l | grep 3 &&
-; RUN: llvm-upgrade < %s | llvm-as | llc -march=x86 | grep rolw | wc -l | grep 1
+; RUN: llc < %s -march=x86 -mcpu=i686 | FileCheck %s
+; RUN: llc < %s -march=x86-64 | FileCheck %s --check-prefix=CHECK64
-declare ushort %llvm.bswap.i16(ushort)
-declare uint %llvm.bswap.i32(uint)
-declare ulong %llvm.bswap.i64(ulong)
+declare i16 @llvm.bswap.i16(i16)
-ushort %W(ushort %A) {
- %Z = call ushort %llvm.bswap.i16(ushort %A)
- ret ushort %Z
+declare i32 @llvm.bswap.i32(i32)
+
+declare i64 @llvm.bswap.i64(i64)
+
+define i16 @W(i16 %A) {
+; CHECK-LABEL: W:
+; CHECK: rolw $8, %ax
+
+; CHECK64-LABEL: W:
+; CHECK64: rolw $8, %
+ %Z = call i16 @llvm.bswap.i16( i16 %A ) ; <i16> [#uses=1]
+ ret i16 %Z
+}
+
+define i32 @X(i32 %A) {
+; CHECK-LABEL: X:
+; CHECK: bswapl %eax
+
+; CHECK64-LABEL: X:
+; CHECK64: bswapl %
+ %Z = call i32 @llvm.bswap.i32( i32 %A ) ; <i32> [#uses=1]
+ ret i32 %Z
+}
+
+define i64 @Y(i64 %A) {
+; CHECK-LABEL: Y:
+; CHECK: bswapl %eax
+; CHECK: bswapl %edx
+
+; CHECK64-LABEL: Y:
+; CHECK64: bswapq %
+ %Z = call i64 @llvm.bswap.i64( i64 %A ) ; <i64> [#uses=1]
+ ret i64 %Z
+}
+
+; rdar://9164521
+define i32 @test1(i32 %a) nounwind readnone {
+entry:
+; CHECK-LABEL: test1:
+; CHECK: bswapl [[REG:%.*]]
+; CHECK: shrl $16, [[REG]]
+
+; CHECK64-LABEL: test1:
+; CHECK64: bswapl [[REG:%.*]]
+; CHECK64: shrl $16, [[REG]]
+ %and = lshr i32 %a, 8
+ %shr3 = and i32 %and, 255
+ %and2 = shl i32 %a, 8
+ %shl = and i32 %and2, 65280
+ %or = or i32 %shr3, %shl
+ ret i32 %or
+}
+
+define i32 @test2(i32 %a) nounwind readnone {
+entry:
+; CHECK-LABEL: test2:
+; CHECK: bswapl [[REG:%.*]]
+; CHECK: sarl $16, [[REG]]
+
+; CHECK64-LABEL: test2:
+; CHECK64: bswapl [[REG:%.*]]
+; CHECK64: sarl $16, [[REG]]
+ %and = lshr i32 %a, 8
+ %shr4 = and i32 %and, 255
+ %and2 = shl i32 %a, 8
+ %or = or i32 %shr4, %and2
+ %sext = shl i32 %or, 16
+ %conv3 = ashr exact i32 %sext, 16
+ ret i32 %conv3
+}
+
+@var8 = global i8 0
+@var16 = global i16 0
+
+; The "shl" below can move bits into the high parts of the value, so the
+; operation is not a "bswap, shr" pair.
+
+; rdar://problem/14814049
+define i64 @not_bswap() {
+; CHECK-LABEL: not_bswap:
+; CHECK-NOT: bswapl
+; CHECK: ret
+
+; CHECK64-LABEL: not_bswap:
+; CHECK64-NOT: bswapq
+; CHECK64: ret
+ %init = load i16, i16* @var16
+ %big = zext i16 %init to i64
+
+ %hishifted = lshr i64 %big, 8
+ %loshifted = shl i64 %big, 8
+
+ %notswapped = or i64 %hishifted, %loshifted
+
+ ret i64 %notswapped
}
-uint %X(uint %A) {
- %Z = call uint %llvm.bswap.i32(uint %A)
- ret uint %Z
+; This time, the lshr (and subsequent or) is completely useless. While it's
+; technically correct to convert this into a "bswap, shr", it's suboptimal. A
+; simple shl works better.
+
+define i64 @not_useful_bswap() {
+; CHECK-LABEL: not_useful_bswap:
+; CHECK-NOT: bswapl
+; CHECK: ret
+
+; CHECK64-LABEL: not_useful_bswap:
+; CHECK64-NOT: bswapq
+; CHECK64: ret
+
+ %init = load i8, i8* @var8
+ %big = zext i8 %init to i64
+
+ %hishifted = lshr i64 %big, 8
+ %loshifted = shl i64 %big, 8
+
+ %notswapped = or i64 %hishifted, %loshifted
+
+ ret i64 %notswapped
}
-ulong %Y(ulong %A) {
- %Z = call ulong %llvm.bswap.i64(ulong %A)
- ret ulong %Z
+; Finally, it *is* OK to just mask off the shl if we know that the value is zero
+; beyond 16 bits anyway. This is a legitimate bswap.
+
+define i64 @finally_useful_bswap() {
+; CHECK-LABEL: finally_useful_bswap:
+; CHECK: bswapl [[REG:%.*]]
+; CHECK: shrl $16, [[REG]]
+; CHECK: ret
+
+; CHECK64-LABEL: finally_useful_bswap:
+; CHECK64: bswapq [[REG:%.*]]
+; CHECK64: shrq $48, [[REG]]
+; CHECK64: ret
+
+ %init = load i16, i16* @var16
+ %big = zext i16 %init to i64
+
+ %hishifted = lshr i64 %big, 8
+ %lomasked = and i64 %big, 255
+ %loshifted = shl i64 %lomasked, 8
+
+ %swapped = or i64 %hishifted, %loshifted
+
+ ret i64 %swapped
}
+
projects / oota-llvm.git / blobdiff