Teach X86 backend to create BMI2 BZHI instructions from (and X, (add (shl 1, Y), -1)). Fixes PR17038.

llvm-svn: 189653

1 files changed, 45 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/bmi.ll b/llvm/test/CodeGen/X86/bmi.ll
index 4eda8888b66..757e98d28d2 100644
--- a/llvm/test/CodeGen/X86/bmi.ll
+++ b/llvm/test/CodeGen/X86/bmi.ll
@@ -146,6 +146,51 @@ define i64 @bzhi64(i64 %x, i64 %y) nounwind readnone {
 
 declare i64 @llvm.x86.bmi.bzhi.64(i64, i64) nounwind readnone
 
+define i32 @bzhi32b(i32 %x, i8 zeroext %index) #0 {
+entry:
+  %conv = zext i8 %index to i32
+  %shl = shl i32 1, %conv
+  %sub = add nsw i32 %shl, -1
+  %and = and i32 %sub, %x
+  ret i32 %and
+; CHECK-LABEL: bzhi32b:
+; CHECK: bzhil
+}
+
+define i32 @bzhi32b_load(i32* %w, i8 zeroext %index) #0 {
+entry:
+  %x = load i32* %w
+  %conv = zext i8 %index to i32
+  %shl = shl i32 1, %conv
+  %sub = add nsw i32 %shl, -1
+  %and = and i32 %sub, %x
+  ret i32 %and
+; CHECK-LABEL: bzhi32b_load:
+; CHECK: bzhil {{.*}}, ({{.*}}), {{.*}}
+}
+
+define i32 @bzhi32c(i32 %x, i8 zeroext %index) #0 {
+entry:
+  %conv = zext i8 %index to i32
+  %shl = shl i32 1, %conv
+  %sub = add nsw i32 %shl, -1
+  %and = and i32 %x, %sub
+  ret i32 %and
+; CHECK-LABEL: bzhi32c:
+; CHECK: bzhil
+}
+
+define i64 @bzhi64b(i64 %x, i8 zeroext %index) #0 {
+entry:
+  %conv = zext i8 %index to i64
+  %shl = shl i64 1, %conv
+  %sub = add nsw i64 %shl, -1
+  %and = and i64 %x, %sub
+  ret i64 %and
+; CHECK-LABEL: bzhi64b:
+; CHECK: bzhiq
+}
+
 define i32 @blsi32(i32 %x) nounwind readnone {
   %tmp = sub i32 0, %x
   %tmp2 = and i32 %x, %tmp