[DAGCombine] Fix for PR37563
While searching for loads to be narrowed, equal sized loads were not
added to the list, resulting in anyext loads not being converted to
zext loads.
https://bugs.llvm.org/show_bug.cgi?id=35763
Differential Revision: https://reviews.llvm.org/D41628
llvm-svn: 321862
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 25ae71c..1fcb010 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3842,9 +3842,16 @@
EVT ExtVT;
if (isAndLoadExtLoad(Mask, Load, Load->getValueType(0), ExtVT) &&
isLegalNarrowLoad(Load, ISD::ZEXTLOAD, ExtVT)) {
- // Only add this load if we can make it more narrow.
- if (ExtVT.bitsLT(Load->getMemoryVT()))
+
+ // ZEXTLOAD is already small enough.
+ if (Load->getExtensionType() == ISD::ZEXTLOAD &&
+ ExtVT.bitsGE(Load->getMemoryVT()))
+ continue;
+
+ // Use LE to convert equal sized loads to zext.
+ if (ExtVT.bitsLE(Load->getMemoryVT()))
Loads.insert(Load);
+
continue;
}
return false;
@@ -3899,11 +3906,13 @@
if (Loads.size() == 0)
return false;
+ DEBUG(dbgs() << "Backwards propagate AND: "; N->dump());
SDValue MaskOp = N->getOperand(1);
// If it exists, fixup the single node we allow in the tree that needs
// masking.
if (FixupNode) {
+ DEBUG(dbgs() << "First, need to fix up: "; FixupNode->dump());
SDValue And = DAG.getNode(ISD::AND, SDLoc(FixupNode),
FixupNode->getValueType(0),
SDValue(FixupNode, 0), MaskOp);
@@ -3922,6 +3931,7 @@
// Create narrow loads.
for (auto *Load : Loads) {
+ DEBUG(dbgs() << "Propagate AND back to: "; Load->dump());
SDValue And = DAG.getNode(ISD::AND, SDLoc(Load), Load->getValueType(0),
SDValue(Load, 0), MaskOp);
DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), And);
diff --git a/llvm/test/CodeGen/ARM/and-load-combine.ll b/llvm/test/CodeGen/ARM/and-load-combine.ll
index 2b92778..69b00ed 100644
--- a/llvm/test/CodeGen/ARM/and-load-combine.ll
+++ b/llvm/test/CodeGen/ARM/and-load-combine.ll
@@ -852,8 +852,7 @@
; ARM: @ %bb.0: @ %entry
; ARM-NEXT: ldrb r0, [r0]
; ARM-NEXT: uxtb r2, r2
-; ARM-NEXT: and r0, r0, r1
-; ARM-NEXT: uxtb r1, r0
+; ARM-NEXT: and r1, r0, r1
; ARM-NEXT: mov r0, #0
; ARM-NEXT: cmp r1, r2
; ARM-NEXT: movweq r0, #1
@@ -863,8 +862,7 @@
; ARMEB: @ %bb.0: @ %entry
; ARMEB-NEXT: ldrb r0, [r0]
; ARMEB-NEXT: uxtb r2, r2
-; ARMEB-NEXT: and r0, r0, r1
-; ARMEB-NEXT: uxtb r1, r0
+; ARMEB-NEXT: and r1, r0, r1
; ARMEB-NEXT: mov r0, #0
; ARMEB-NEXT: cmp r1, r2
; ARMEB-NEXT: movweq r0, #1
@@ -872,9 +870,8 @@
;
; THUMB1-LABEL: test6:
; THUMB1: @ %bb.0: @ %entry
-; THUMB1-NEXT: ldrb r0, [r0]
-; THUMB1-NEXT: ands r0, r1
-; THUMB1-NEXT: uxtb r3, r0
+; THUMB1-NEXT: ldrb r3, [r0]
+; THUMB1-NEXT: ands r3, r1
; THUMB1-NEXT: uxtb r2, r2
; THUMB1-NEXT: movs r0, #1
; THUMB1-NEXT: movs r1, #0
@@ -889,8 +886,7 @@
; THUMB2: @ %bb.0: @ %entry
; THUMB2-NEXT: ldrb r0, [r0]
; THUMB2-NEXT: uxtb r2, r2
-; THUMB2-NEXT: ands r0, r1
-; THUMB2-NEXT: uxtb r1, r0
+; THUMB2-NEXT: ands r1, r0
; THUMB2-NEXT: movs r0, #0
; THUMB2-NEXT: cmp r1, r2
; THUMB2-NEXT: it eq
diff --git a/llvm/test/CodeGen/X86/pr37563.ll b/llvm/test/CodeGen/X86/pr37563.ll
index f909eca..934902d 100644
--- a/llvm/test/CodeGen/X86/pr37563.ll
+++ b/llvm/test/CodeGen/X86/pr37563.ll
@@ -10,9 +10,10 @@
define void @PR35763() {
; CHECK-LABEL: PR35763:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: movzwl z+{{.*}}(%rip), %eax
-; CHECK-NEXT: orl {{.*}}(%rip), %eax
-; CHECK-NEXT: movq %rax, {{.*}}(%rip)
+; CHECK-NEXT: movzwl {{.*}}(%rip), %eax
+; CHECK-NEXT: movzwl z+{{.*}}(%rip), %ecx
+; CHECK-NEXT: orl %eax, %ecx
+; CHECK-NEXT: movq %rcx, {{.*}}(%rip)
; CHECK-NEXT: movl z+{{.*}}(%rip), %eax
; CHECK-NEXT: movzbl z+{{.*}}(%rip), %ecx
; CHECK-NEXT: shlq $32, %rcx