[InstSimplify] Simplify comparison between zext(x) and sext(x)
This is picking up a loose thread from D69006: We can simplify
(zext x) ule (sext x) and (zext x) sge (sext x) to true, with
various permutations. Oddly, SCEV knows about this identity,
but nothing on the IR level does.
Differential Revision: https://reviews.llvm.org/D83081
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 817d23a..df4abe0 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3404,6 +3404,15 @@
MaxRecurse-1))
return V;
}
+ // Fold (zext X) ule (sext X), (zext X) sge (sext X) to true.
+ else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
+ if (SrcOp == RI->getOperand(0)) {
+ if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE)
+ return ConstantInt::getTrue(ITy);
+ if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT)
+ return ConstantInt::getFalse(ITy);
+ }
+ }
// Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
@@ -3463,6 +3472,15 @@
Q, MaxRecurse-1))
return V;
}
+ // Fold (sext X) uge (zext X), (sext X) sle (zext X) to true.
+ else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
+ if (SrcOp == RI->getOperand(0)) {
+ if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE)
+ return ConstantInt::getTrue(ITy);
+ if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT)
+ return ConstantInt::getFalse(ITy);
+ }
+ }
// Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
diff --git a/llvm/test/Transforms/InstSimplify/cmp_ext.ll b/llvm/test/Transforms/InstSimplify/cmp_ext.ll
index 4bbe23b..63d3652 100644
--- a/llvm/test/Transforms/InstSimplify/cmp_ext.ll
+++ b/llvm/test/Transforms/InstSimplify/cmp_ext.ll
@@ -16,10 +16,7 @@
define i1 @zext_ugt_sext(i32 %x) {
; CHECK-LABEL: @zext_ugt_sext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[ZEXT]], [[SEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -42,10 +39,7 @@
define i1 @zext_ule_sext(i32 %x) {
; CHECK-LABEL: @zext_ule_sext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp ule i64 [[ZEXT]], [[SEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -55,10 +49,7 @@
define i1 @zext_sge_sext(i32 %x) {
; CHECK-LABEL: @zext_sge_sext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp sge i64 [[ZEXT]], [[SEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -81,10 +72,7 @@
define i1 @zext_slt_sext(i32 %x) {
; CHECK-LABEL: @zext_slt_sext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[ZEXT]], [[SEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -107,10 +95,7 @@
define i1 @sext_uge_zext(i32 %x) {
; CHECK-LABEL: @sext_uge_zext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp uge i64 [[SEXT]], [[ZEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -133,10 +118,7 @@
define i1 @sext_ult_zext(i32 %x) {
; CHECK-LABEL: @sext_ult_zext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[SEXT]], [[ZEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -172,10 +154,7 @@
define i1 @sext_sgt_zext(i32 %x) {
; CHECK-LABEL: @sext_sgt_zext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[SEXT]], [[ZEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -198,10 +177,7 @@
define i1 @sext_sle_zext(i32 %x) {
; CHECK-LABEL: @sext_sle_zext(
-; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[X:%.*]] to i64
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[X]] to i64
-; CHECK-NEXT: [[CMP:%.*]] = icmp sle i64 [[SEXT]], [[ZEXT]]
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%sext = sext i32 %x to i64
%zext = zext i32 %x to i64
@@ -211,10 +187,7 @@
define <4 x i1> @zext_ugt_sext_vec(<4 x i32> %x) {
; CHECK-LABEL: @zext_ugt_sext_vec(
-; CHECK-NEXT: [[SEXT:%.*]] = sext <4 x i32> [[X:%.*]] to <4 x i64>
-; CHECK-NEXT: [[ZEXT:%.*]] = zext <4 x i32> [[X]] to <4 x i64>
-; CHECK-NEXT: [[CMP:%.*]] = icmp ugt <4 x i64> [[ZEXT]], [[SEXT]]
-; CHECK-NEXT: ret <4 x i1> [[CMP]]
+; CHECK-NEXT: ret <4 x i1> zeroinitializer
;
%sext = sext <4 x i32> %x to <4 x i64>
%zext = zext <4 x i32> %x to <4 x i64>
@@ -224,10 +197,7 @@
define <4 x i1> @sext_ult_zext_vec(<4 x i32> %x) {
; CHECK-LABEL: @sext_ult_zext_vec(
-; CHECK-NEXT: [[SEXT:%.*]] = sext <4 x i32> [[X:%.*]] to <4 x i64>
-; CHECK-NEXT: [[ZEXT:%.*]] = zext <4 x i32> [[X]] to <4 x i64>
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult <4 x i64> [[SEXT]], [[ZEXT]]
-; CHECK-NEXT: ret <4 x i1> [[CMP]]
+; CHECK-NEXT: ret <4 x i1> zeroinitializer
;
%sext = sext <4 x i32> %x to <4 x i64>
%zext = zext <4 x i32> %x to <4 x i64>
