Transform (x << (y&31)) -> (x << y). This takes advantage of the fact x86 shift instructions 2nd operand (shift count) is limited to 0 to 31 (or 63 in the x86-64 case).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55558 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/test/CodeGen/X86/shift-and.ll b/test/CodeGen/X86/shift-and.ll
new file mode 100644
index 0000000000..b6d78a4857
--- /dev/null
+++ b/test/CodeGen/X86/shift-and.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | llc -march=x86    | grep and | count 1
+; RUN: llvm-as < %s | llc -march=x86-64 | not grep and 
+
+define i32 @t1(i32 %t, i32 %val) nounwind {
+       %shamt = and i32 %t, 31
+       %res = shl i32 %val, %shamt
+       ret i32 %res
+}
+
+@X = internal global i16 0
+
+define void @t2(i16 %t) nounwind {
+       %shamt = and i16 %t, 31
+       %tmp = load i16* @X
+       %tmp1 = ashr i16 %tmp, %shamt
+       store i16 %tmp1, i16* @X
+       ret void
+}
+
+define i64 @t3(i64 %t, i64 %val) nounwind {
+       %shamt = and i64 %t, 63
+       %res = lshr i64 %val, %shamt
+       ret i64 %res
+}