[llvm] a258338 - [X86] Add test cases for missed opportunity to use a byte test instruction instead of an xor with 0 in parity patterns.

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2020-08-02T10:45:04-07:00
New Revision: a258338d627170f204c40ebe93ea7fb18c7c1197

URL: https://github.com/llvm/llvm-project/commit/a258338d627170f204c40ebe93ea7fb18c7c1197
DIFF: https://github.com/llvm/llvm-project/commit/a258338d627170f204c40ebe93ea7fb18c7c1197.diff

LOG: [X86] Add test cases for missed opportunity to use a byte test instruction instead of an xor with 0 in parity patterns.

If the input to the ctpop fits in 8 bits, we can use the parity
flag from a TEST instruction, but we're currently XORing with 0.

Added: 
    

Modified: 
    llvm/test/CodeGen/X86/parity.ll

Removed: 
    


################################################################################
diff  --git a/llvm/test/CodeGen/X86/parity.ll b/llvm/test/CodeGen/X86/parity.ll
index 8637058e0680..68f2b8b1b553 100644
--- a/llvm/test/CodeGen/X86/parity.ll
+++ b/llvm/test/CodeGen/X86/parity.ll
@@ -181,5 +181,75 @@ define i8 @parity_32_trunc(i32 %x) {
   ret i8 %3
 }
 
+define i32 @parity_8_zext(i8 %x) {
+; X86-NOPOPCNT-LABEL: parity_8_zext:
+; X86-NOPOPCNT:       # %bb.0:
+; X86-NOPOPCNT-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-NOPOPCNT-NEXT:    xorl %eax, %eax
+; X86-NOPOPCNT-NEXT:    xorb $0, %cl
+; X86-NOPOPCNT-NEXT:    setnp %al
+; X86-NOPOPCNT-NEXT:    retl
+;
+; X64-NOPOPCNT-LABEL: parity_8_zext:
+; X64-NOPOPCNT:       # %bb.0:
+; X64-NOPOPCNT-NEXT:    xorl %eax, %eax
+; X64-NOPOPCNT-NEXT:    xorb $0, %dil
+; X64-NOPOPCNT-NEXT:    setnp %al
+; X64-NOPOPCNT-NEXT:    retq
+;
+; X86-POPCNT-LABEL: parity_8_zext:
+; X86-POPCNT:       # %bb.0:
+; X86-POPCNT-NEXT:    movzbl {{[0-9]+}}(%esp), %eax
+; X86-POPCNT-NEXT:    popcntl %eax, %eax
+; X86-POPCNT-NEXT:    andl $1, %eax
+; X86-POPCNT-NEXT:    retl
+;
+; X64-POPCNT-LABEL: parity_8_zext:
+; X64-POPCNT:       # %bb.0:
+; X64-POPCNT-NEXT:    movzbl %dil, %eax
+; X64-POPCNT-NEXT:    popcntl %eax, %eax
+; X64-POPCNT-NEXT:    andl $1, %eax
+; X64-POPCNT-NEXT:    retq
+  %a = zext i8 %x to i32
+  %b = tail call i32 @llvm.ctpop.i32(i32 %a)
+  %c = and i32 %b, 1
+  ret i32 %c
+}
+
+define i32 @parity_8_mask(i32 %x) {
+; X86-NOPOPCNT-LABEL: parity_8_mask:
+; X86-NOPOPCNT:       # %bb.0:
+; X86-NOPOPCNT-NEXT:    movb {{[0-9]+}}(%esp), %cl
+; X86-NOPOPCNT-NEXT:    xorl %eax, %eax
+; X86-NOPOPCNT-NEXT:    xorb $0, %cl
+; X86-NOPOPCNT-NEXT:    setnp %al
+; X86-NOPOPCNT-NEXT:    retl
+;
+; X64-NOPOPCNT-LABEL: parity_8_mask:
+; X64-NOPOPCNT:       # %bb.0:
+; X64-NOPOPCNT-NEXT:    xorl %eax, %eax
+; X64-NOPOPCNT-NEXT:    xorb $0, %dil
+; X64-NOPOPCNT-NEXT:    setnp %al
+; X64-NOPOPCNT-NEXT:    retq
+;
+; X86-POPCNT-LABEL: parity_8_mask:
+; X86-POPCNT:       # %bb.0:
+; X86-POPCNT-NEXT:    movzbl {{[0-9]+}}(%esp), %eax
+; X86-POPCNT-NEXT:    popcntl %eax, %eax
+; X86-POPCNT-NEXT:    andl $1, %eax
+; X86-POPCNT-NEXT:    retl
+;
+; X64-POPCNT-LABEL: parity_8_mask:
+; X64-POPCNT:       # %bb.0:
+; X64-POPCNT-NEXT:    movzbl %dil, %eax
+; X64-POPCNT-NEXT:    popcntl %eax, %eax
+; X64-POPCNT-NEXT:    andl $1, %eax
+; X64-POPCNT-NEXT:    retq
+  %a = and i32 %x, 255
+  %b = tail call i32 @llvm.ctpop.i32(i32 %a)
+  %c = and i32 %b, 1
+  ret i32 %c
+}
+
 declare i32 @llvm.ctpop.i32(i32 %x)
 declare i64 @llvm.ctpop.i64(i64 %x)