X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=test%2FCodeGen%2FX86%2Fbswap.ll;h=48dc18e0ac1448140e22abc3053bb28a22ee4632;hb=c8e72e912627d9276b3cf7c43169d565a0f5a74e;hp=d48d26568cdb5a27cb5dcb11e00c2140558d1dec;hpb=d88fc03602947b5baa35c8b09fe8bcfa2b4a03c1;p=oota-llvm.git

diff --git a/test/CodeGen/X86/bswap.ll b/test/CodeGen/X86/bswap.ll
index d48d26568cd..48dc18e0ac1 100644
--- a/test/CodeGen/X86/bswap.ll
+++ b/test/CodeGen/X86/bswap.ll
@@ -1,23 +1,154 @@
 ; bswap should be constant folded when it is passed a constant argument
 
-; RUN: llvm-as < %s | llc -march=x86 -enable-x86-dag-isel | grep bswapl | wc -l | grep 3 &&
-; RUN: llvm-as < %s | llc -march=x86 -enable-x86-dag-isel | 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
 }
+