Bypass Slow Divides

* Only apply divide bypass optimization when not optimizing for size. 
* Fixed bug caused by constant for 0 value of type Int32,
  used dividend type to generate the constant instead.
* For atom x86-64 apply the divide bypass to use 16-bit divides instead of
  64-bit divides when operand values are small enough.
* Added lit tests for 64-bit divide bypass.

Patch by Tyler Nowicki!




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176442 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 46 insertions, 0 deletions

diff --git a/test/CodeGen/X86/atom-bypass-slow-division-64.ll b/test/CodeGen/X86/atom-bypass-slow-division-64.ll
new file mode 100644
index 0000000..a3bbea3
--- /dev/null
+++ b/test/CodeGen/X86/atom-bypass-slow-division-64.ll
@@ -0,0 +1,46 @@
+; RUN: llc < %s -mcpu=atom -mtriple=i686-linux -march=x86-64 | FileCheck %s
+
+; Additional tests for 64-bit divide bypass
+
+define i64 @Test_get_quotient(i64 %a, i64 %b) nounwind {
+; CHECK: Test_get_quotient:
+; CHECK: orq %rsi, %rcx
+; CHECK-NEXT: testq $-65536, %rcx
+; CHECK-NEXT: je
+; CHECK: idivq
+; CHECK: ret
+; CHECK: divw
+; CHECK: ret
+  %result = sdiv i64 %a, %b
+  ret i64 %result
+}
+
+define i64 @Test_get_remainder(i64 %a, i64 %b) nounwind {
+; CHECK: Test_get_remainder:
+; CHECK: orq %rsi, %rcx
+; CHECK-NEXT: testq $-65536, %rcx
+; CHECK-NEXT: je
+; CHECK: idivq
+; CHECK: ret
+; CHECK: divw
+; CHECK: ret
+  %result = srem i64 %a, %b
+  ret i64 %result
+}
+
+define i64 @Test_get_quotient_and_remainder(i64 %a, i64 %b) nounwind {
+; CHECK: Test_get_quotient_and_remainder:
+; CHECK: orq %rsi, %rcx
+; CHECK-NEXT: testq $-65536, %rcx
+; CHECK-NEXT: je
+; CHECK: idivq
+; CHECK: divw
+; CHECK: addq
+; CHECK: ret
+; CHECK-NOT: idivq
+; CHECK-NOT: divw
+  %resultdiv = sdiv i64 %a, %b
+  %resultrem = srem i64 %a, %b
+  %result = add i64 %resultdiv, %resultrem
+  ret i64 %result
+}