This is another case where instcombine demanded bits optimization created

large immediates. Add dag combine logic to recover in case the large
immediates doesn't fit in cmp immediate operand field.

int foo(unsigned long l) {
  return (l>> 47) == 1;
}

we produce

  %shr.mask = and i64 %l, -140737488355328
  %cmp = icmp eq i64 %shr.mask, 140737488355328
  %conv = zext i1 %cmp to i32
  ret i32 %conv

which codegens to

movq    $0xffff800000000000,%rax
andq    %rdi,%rax
movq    $0x0000800000000000,%rcx
cmpq    %rcx,%rax
sete    %al
movzbl    %al,%eax
ret

TargetLowering::SimplifySetCC would transform
(X & -256) == 256 -> (X >> 8) == 1
if the immediate fails the isLegalICmpImmediate() test. For x86,
that's immediates which are not a signed 32-bit immediate.

Based on a patch by Eli Friedman.

PR10328
rdar://9758774


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160346 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 4 deletions

diff --git a/test/CodeGen/X86/cmp.ll b/test/CodeGen/X86/cmp.ll
index c9c85ab..8343cec 100644
--- a/test/CodeGen/X86/cmp.ll
+++ b/test/CodeGen/X86/cmp.ll
@@ -91,7 +91,7 @@ F:
 }
 
 ; rdar://11866926
-define i32 @test7(i64 %res) nounwind uwtable readnone ssp {
+define i32 @test7(i64 %res) nounwind {
 entry:
 ; CHECK: test7:
 ; CHECK-NOT: movabsq
@@ -103,7 +103,7 @@ entry:
   ret i32 %lnot.ext
 }
 
-define i32 @test8(i64 %res) nounwind uwtable readnone ssp {
+define i32 @test8(i64 %res) nounwind {
 entry:
 ; CHECK: test8:
 ; CHECK-NOT: movabsq
@@ -114,7 +114,7 @@ entry:
   ret i32 %lnot.ext
 }
 
-define i32 @test9(i64 %res) nounwind uwtable readnone ssp {
+define i32 @test9(i64 %res) nounwind {
 entry:
 ; CHECK: test9:
 ; CHECK-NOT: movabsq
@@ -126,7 +126,7 @@ entry:
   ret i32 %lnot.ext
 }
 
-define i32 @test10(i64 %res) nounwind uwtable readnone ssp {
+define i32 @test10(i64 %res) nounwind {
 entry:
 ; CHECK: test10:
 ; CHECK-NOT: movabsq
@@ -138,3 +138,16 @@ entry:
   ret i32 %lnot.ext
 }
 
+; rdar://9758774
+define i32 @test11(i64 %l) nounwind {
+entry:
+; CHECK: test11:
+; CHECK-NOT: movabsq
+; CHECK-NOT: andq
+; CHECK: shrq $47, %rdi
+; CHECK: cmpq $1, %rdi
+  %shr.mask = and i64 %l, -140737488355328
+  %cmp = icmp eq i64 %shr.mask, 140737488355328
+  %conv = zext i1 %cmp to i32
+  ret i32 %conv
+}