[llvm] 99387e3 - [InstCombine] Add transforms for `(icmp uPred (trunc x),(truncOrZext(y)))`->`(icmp uPred x,y)`
Noah Goldstein via llvm-commits
llvm-commits at lists.llvm.org
Sun Nov 19 10:15:31 PST 2023
Author: Noah Goldstein
Date: 2023-11-19T12:15:04-06:00
New Revision: 99387e33dc750b35223a86f59f755d41d8614bd5
URL: https://github.com/llvm/llvm-project/commit/99387e33dc750b35223a86f59f755d41d8614bd5
DIFF: https://github.com/llvm/llvm-project/commit/99387e33dc750b35223a86f59f755d41d8614bd5.diff
LOG: [InstCombine] Add transforms for `(icmp uPred (trunc x),(truncOrZext(y)))`->`(icmp uPred x,y)`
Three transforms (all commutative):
https://alive2.llvm.org/ce/z/Bc-nh4
Closes #71309
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/lib/Transforms/InstCombine/InstCombineInternal.h
llvm/test/Transforms/InstCombine/eq-of-parts.ll
llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 9bc84c7dd6e1539..783668db2da7670 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1512,6 +1512,61 @@ Instruction *InstCombinerImpl::foldICmpTruncConstant(ICmpInst &Cmp,
return nullptr;
}
+/// Fold icmp (trunc X), (trunc Y).
+/// Fold icmp (trunc X), (zext Y).
+Instruction *
+InstCombinerImpl::foldICmpTruncWithTruncOrExt(ICmpInst &Cmp,
+ const SimplifyQuery &Q) {
+ if (Cmp.isSigned())
+ return nullptr;
+
+ Value *X, *Y;
+ ICmpInst::Predicate Pred;
+ bool YIsZext = false;
+ // Try to match icmp (trunc X), (trunc Y)
+ if (match(&Cmp, m_ICmp(Pred, m_Trunc(m_Value(X)), m_Trunc(m_Value(Y))))) {
+ if (X->getType() != Y->getType() &&
+ (!Cmp.getOperand(0)->hasOneUse() || !Cmp.getOperand(1)->hasOneUse()))
+ return nullptr;
+ if (!isDesirableIntType(X->getType()->getScalarSizeInBits()) &&
+ isDesirableIntType(Y->getType()->getScalarSizeInBits())) {
+ std::swap(X, Y);
+ Pred = Cmp.getSwappedPredicate(Pred);
+ }
+ }
+ // Try to match icmp (trunc X), (zext Y)
+ else if (match(&Cmp, m_c_ICmp(Pred, m_Trunc(m_Value(X)),
+ m_OneUse(m_ZExt(m_Value(Y))))))
+
+ YIsZext = true;
+ else
+ return nullptr;
+
+ Type *TruncTy = Cmp.getOperand(0)->getType();
+ unsigned TruncBits = TruncTy->getScalarSizeInBits();
+
+ // If this transform will end up changing from desirable types -> undesirable
+ // types skip it.
+ if (isDesirableIntType(TruncBits) &&
+ !isDesirableIntType(X->getType()->getScalarSizeInBits()))
+ return nullptr;
+
+ // Check if the trunc is unneeded.
+ KnownBits KnownX = llvm::computeKnownBits(X, /*Depth*/ 0, Q);
+ if (KnownX.countMaxActiveBits() > TruncBits)
+ return nullptr;
+
+ if (!YIsZext) {
+ // If Y is also a trunc, make sure it is unneeded.
+ KnownBits KnownY = llvm::computeKnownBits(Y, /*Depth*/ 0, Q);
+ if (KnownY.countMaxActiveBits() > TruncBits)
+ return nullptr;
+ }
+
+ Value *NewY = Builder.CreateZExtOrTrunc(Y, X->getType());
+ return new ICmpInst(Pred, X, NewY);
+}
+
/// Fold icmp (xor X, Y), C.
Instruction *InstCombinerImpl::foldICmpXorConstant(ICmpInst &Cmp,
BinaryOperator *Xor,
@@ -6879,6 +6934,9 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
if (Instruction *Res = foldICmpUsingKnownBits(I))
return Res;
+ if (Instruction *Res = foldICmpTruncWithTruncOrExt(I, Q))
+ return Res;
+
// Test if the ICmpInst instruction is used exclusively by a select as
// part of a minimum or maximum operation. If so, refrain from doing
// any other folding. This helps out other analyses which understand
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 68a8fb676d8d909..0bbb22be71569f6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -647,6 +647,8 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
ConstantInt *C);
Instruction *foldICmpTruncConstant(ICmpInst &Cmp, TruncInst *Trunc,
const APInt &C);
+ Instruction *foldICmpTruncWithTruncOrExt(ICmpInst &Cmp,
+ const SimplifyQuery &Q);
Instruction *foldICmpAndConstant(ICmpInst &Cmp, BinaryOperator *And,
const APInt &C);
Instruction *foldICmpXorConstant(ICmpInst &Cmp, BinaryOperator *Xor,
diff --git a/llvm/test/Transforms/InstCombine/eq-of-parts.ll b/llvm/test/Transforms/InstCombine/eq-of-parts.ll
index 57b15ae3b96e66e..217e37b85933949 100644
--- a/llvm/test/Transforms/InstCombine/eq-of-parts.ll
+++ b/llvm/test/Transforms/InstCombine/eq-of-parts.ll
@@ -584,17 +584,8 @@ define i1 @eq_21_not_adjacent(i32 %x, i32 %y) {
define i1 @eq_shift_in_zeros(i32 %x, i32 %y) {
; CHECK-LABEL: @eq_shift_in_zeros(
-; CHECK-NEXT: [[X_321:%.*]] = lshr i32 [[X:%.*]], 8
-; CHECK-NEXT: [[X_1:%.*]] = trunc i32 [[X_321]] to i8
-; CHECK-NEXT: [[X_32:%.*]] = lshr i32 [[X]], 16
-; CHECK-NEXT: [[X_2:%.*]] = trunc i32 [[X_32]] to i24
-; CHECK-NEXT: [[Y_321:%.*]] = lshr i32 [[Y:%.*]], 8
-; CHECK-NEXT: [[Y_1:%.*]] = trunc i32 [[Y_321]] to i8
-; CHECK-NEXT: [[Y_32:%.*]] = lshr i32 [[Y]], 16
-; CHECK-NEXT: [[Y_2:%.*]] = trunc i32 [[Y_32]] to i24
-; CHECK-NEXT: [[C_1:%.*]] = icmp eq i8 [[X_1]], [[Y_1]]
-; CHECK-NEXT: [[C_2:%.*]] = icmp eq i24 [[X_2]], [[Y_2]]
-; CHECK-NEXT: [[C_210:%.*]] = and i1 [[C_2]], [[C_1]]
+; CHECK-NEXT: [[C_210_UNSHIFTED:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[C_210:%.*]] = icmp ult i32 [[C_210_UNSHIFTED]], 256
; CHECK-NEXT: ret i1 [[C_210]]
;
%x.321 = lshr i32 %x, 8
@@ -1249,17 +1240,8 @@ define i1 @ne_21_not_adjacent(i32 %x, i32 %y) {
define i1 @ne_shift_in_zeros(i32 %x, i32 %y) {
; CHECK-LABEL: @ne_shift_in_zeros(
-; CHECK-NEXT: [[X_321:%.*]] = lshr i32 [[X:%.*]], 8
-; CHECK-NEXT: [[X_1:%.*]] = trunc i32 [[X_321]] to i8
-; CHECK-NEXT: [[X_32:%.*]] = lshr i32 [[X]], 16
-; CHECK-NEXT: [[X_2:%.*]] = trunc i32 [[X_32]] to i24
-; CHECK-NEXT: [[Y_321:%.*]] = lshr i32 [[Y:%.*]], 8
-; CHECK-NEXT: [[Y_1:%.*]] = trunc i32 [[Y_321]] to i8
-; CHECK-NEXT: [[Y_32:%.*]] = lshr i32 [[Y]], 16
-; CHECK-NEXT: [[Y_2:%.*]] = trunc i32 [[Y_32]] to i24
-; CHECK-NEXT: [[C_1:%.*]] = icmp ne i8 [[X_1]], [[Y_1]]
-; CHECK-NEXT: [[C_2:%.*]] = icmp ne i24 [[X_2]], [[Y_2]]
-; CHECK-NEXT: [[C_210:%.*]] = or i1 [[C_2]], [[C_1]]
+; CHECK-NEXT: [[C_210_UNSHIFTED:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[C_210:%.*]] = icmp ugt i32 [[C_210_UNSHIFTED]], 255
; CHECK-NEXT: ret i1 [[C_210]]
;
%x.321 = lshr i32 %x, 8
diff --git a/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll b/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
index 7cce1320e7b4b97..85f67bfa335bb87 100644
--- a/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-of-trunc-ext.ll
@@ -9,9 +9,7 @@ define i1 @icmp_trunc_x_trunc_y(i32 %x, i32 %y) {
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i32 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = trunc i32 [[Y]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT: [[R:%.*]] = icmp eq i32 [[X]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i32 %x, 65536
@@ -51,9 +49,8 @@ define i1 @icmp_trunc_x_trunc_y_illegal_trunc_to_legal_anyways(i123 %x, i32 %y)
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i123 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = trunc i32 [[Y]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp eq i16 [[X16]], [[Y16]]
+; CHECK-NEXT: [[TMP1:%.*]] = trunc i123 [[X]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp eq i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i123 %x, 65536
@@ -72,9 +69,8 @@ define i1 @icmp_trunc_x_trunc_y_2_illegal_anyways(i33 %x, i63 %y) {
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i63 [[Y:%.*]], 512
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i33 [[X]] to i9
-; CHECK-NEXT: [[Y16:%.*]] = trunc i63 [[Y]] to i9
-; CHECK-NEXT: [[R:%.*]] = icmp ult i9 [[Y16]], [[X16]]
+; CHECK-NEXT: [[TMP1:%.*]] = zext nneg i33 [[X]] to i63
+; CHECK-NEXT: [[R:%.*]] = icmp ugt i63 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i33 %x, 512
@@ -93,9 +89,8 @@ define i1 @icmp_trunc_x_trunc_y_3(i64 %x, i32 %y) {
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 256
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[XI8:%.*]] = trunc i64 [[X]] to i8
-; CHECK-NEXT: [[YI8:%.*]] = trunc i32 [[Y]] to i8
-; CHECK-NEXT: [[R:%.*]] = icmp ule i8 [[YI8]], [[XI8]]
+; CHECK-NEXT: [[TMP1:%.*]] = trunc i64 [[X]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp uge i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i64 %x, 123
@@ -156,9 +151,8 @@ define i1 @icmp_trunc_x_trunc_y_swap0(i33 %x, i32 %y) {
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i33 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = trunc i32 [[Y]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp ule i16 [[X16]], [[Y16]]
+; CHECK-NEXT: [[TMP1:%.*]] = trunc i33 [[X]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp ule i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i33 %x, 65536
@@ -177,9 +171,8 @@ define i1 @icmp_trunc_x_trunc_y_swap1(i33 %x, i32 %y) {
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i33 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = trunc i32 [[Y]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp ule i16 [[Y16]], [[X16]]
+; CHECK-NEXT: [[TMP1:%.*]] = trunc i33 [[X]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp uge i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i33 %x, 65536
@@ -196,9 +189,8 @@ define i1 @icmp_trunc_x_zext_y(i32 %x, i8 %y) {
; CHECK-LABEL: @icmp_trunc_x_zext_y(
; CHECK-NEXT: [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i32 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = zext i8 [[Y:%.*]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp ugt i16 [[X16]], [[Y16]]
+; CHECK-NEXT: [[TMP1:%.*]] = zext i8 [[Y:%.*]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp ult i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i32 %x, 65536
@@ -213,9 +205,8 @@ define i1 @icmp_trunc_x_zext_y_2(i32 %x, i8 %y) {
; CHECK-LABEL: @icmp_trunc_x_zext_y_2(
; CHECK-NEXT: [[X_LB_ONLY:%.*]] = icmp ult i32 [[X:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[X_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = trunc i32 [[X]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = zext i8 [[Y:%.*]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp uge i16 [[Y16]], [[X16]]
+; CHECK-NEXT: [[TMP1:%.*]] = zext i8 [[Y:%.*]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp uge i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_lb_only = icmp ult i32 %x, 65536
@@ -230,9 +221,8 @@ define i1 @icmp_trunc_x_zext_y_3(i6 %x, i32 %y) {
; CHECK-LABEL: @icmp_trunc_x_zext_y_3(
; CHECK-NEXT: [[Y_LB_ONLY:%.*]] = icmp ult i32 [[Y:%.*]], 65536
; CHECK-NEXT: call void @llvm.assume(i1 [[Y_LB_ONLY]])
-; CHECK-NEXT: [[X16:%.*]] = zext i6 [[X:%.*]] to i16
-; CHECK-NEXT: [[Y16:%.*]] = trunc i32 [[Y]] to i16
-; CHECK-NEXT: [[R:%.*]] = icmp ne i16 [[Y16]], [[X16]]
+; CHECK-NEXT: [[TMP1:%.*]] = zext i6 [[X:%.*]] to i32
+; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%y_lb_only = icmp ult i32 %y, 65536
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