[PATCH] D46494: [DAGCombiner] Masked merge: enhance handling of 'andn' with immediates
Roman Lebedev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon May 7 09:49:00 PDT 2018
lebedev.ri updated this revision to Diff 145493.
lebedev.ri marked an inline comment as done.
lebedev.ri added a comment.
Rebased.
Repository:
rL LLVM
https://reviews.llvm.org/D46494
Files:
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
test/CodeGen/X86/unfold-masked-merge-scalar-variablemask.ll
Index: test/CodeGen/X86/unfold-masked-merge-scalar-variablemask.ll
===================================================================
--- test/CodeGen/X86/unfold-masked-merge-scalar-variablemask.ll
+++ test/CodeGen/X86/unfold-masked-merge-scalar-variablemask.ll
@@ -657,10 +657,9 @@
;
; CHECK-BMI-LABEL: in_constant_varx_42:
; CHECK-BMI: # %bb.0:
-; CHECK-BMI-NEXT: xorl $42, %edi
-; CHECK-BMI-NEXT: andl %edx, %edi
-; CHECK-BMI-NEXT: xorl $42, %edi
-; CHECK-BMI-NEXT: movl %edi, %eax
+; CHECK-BMI-NEXT: andnl %edx, %edi, %eax
+; CHECK-BMI-NEXT: orl $42, %edx
+; CHECK-BMI-NEXT: andnl %edx, %eax, %eax
; CHECK-BMI-NEXT: retq
%n0 = xor i32 %x, 42 ; %x
%n1 = and i32 %n0, %mask
@@ -704,9 +703,10 @@
;
; CHECK-BMI-LABEL: in_constant_varx_42_invmask:
; CHECK-BMI: # %bb.0:
-; CHECK-BMI-NEXT: xorl $42, %edi
-; CHECK-BMI-NEXT: andnl %edi, %edx, %eax
-; CHECK-BMI-NEXT: xorl $42, %eax
+; CHECK-BMI-NEXT: notl %edx
+; CHECK-BMI-NEXT: andnl %edx, %edi, %eax
+; CHECK-BMI-NEXT: orl $42, %edx
+; CHECK-BMI-NEXT: andnl %edx, %eax, %eax
; CHECK-BMI-NEXT: retq
%notmask = xor i32 %mask, -1
%n0 = xor i32 %x, 42 ; %x
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5372,6 +5372,9 @@
// | D |
// Into:
// (x & m) | (y & ~m)
+// If y is a constant, and the 'andn' does not work with immediates,
+// we unfold into a different pattern:
+// ~(~x & m) & (m | y)
// NOTE: we don't unfold the pattern if 'xor' is actually a 'not', because at
// the very least that breaks andnpd / andnps patterns, and because those
// patterns are simplified in IR and shouldn't be created in the DAG
@@ -5428,12 +5431,19 @@
if (!TLI.hasAndNot(M))
return SDValue();
- // If Y is a constant, check that 'andn' works with immediates.
- if (!TLI.hasAndNot(Y))
- return SDValue();
-
SDLoc DL(N);
+ // If Y is a constant, check that 'andn' works with immediates.
+ if (!TLI.hasAndNot(Y)) {
+ assert(TLI.hasAndNot(X) && "Only mask is a variable? Unreachable.");
+ // If not, we need to do a bit more work to make sure andn is still used.
+ SDValue NotX = DAG.getNOT(DL, X, VT);
+ SDValue LHS = DAG.getNode(ISD::AND, DL, VT, NotX, M);
+ SDValue NotLHS = DAG.getNOT(DL, LHS, VT);
+ SDValue RHS = DAG.getNode(ISD::OR, DL, VT, M, Y);
+ return DAG.getNode(ISD::AND, DL, VT, NotLHS, RHS);
+ }
+
SDValue LHS = DAG.getNode(ISD::AND, DL, VT, X, M);
SDValue NotM = DAG.getNOT(DL, M, VT);
SDValue RHS = DAG.getNode(ISD::AND, DL, VT, Y, NotM);
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D46494.145493.patch
Type: text/x-patch
Size: 2712 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180507/bf56183a/attachment.bin>
More information about the llvm-commits
mailing list