[llvm] Enable FoldOpIntoSelect when the Op's other parameter is non-const (PR #166102)
Gábor Spaits via llvm-commits
llvm-commits at lists.llvm.org
Sun Nov 2 14:14:07 PST 2025
https://github.com/spaits created https://github.com/llvm/llvm-project/pull/166102
This patch enables `FoldOpIntoSelect` for the cases when Op's second parameter is a non-constant.
NOTE:
This is a draft patch, since I don't have the resources to run the full `chech-llvm` suite, so there may be failing tests that I find here first.
>From 6340c84d48ba4fd3357b7e63379d0d92eec32080 Mon Sep 17 00:00:00 2001
From: Gabor Spaits <gaborspaits1 at gmail.com>
Date: Sun, 2 Nov 2025 21:59:06 +0100
Subject: [PATCH] Enable FoldOpIntoSelect when the Op's other parameter is
non-const
---
.../Transforms/InstCombine/InstructionCombining.cpp | 5 ++---
llvm/test/Transforms/InstCombine/binop-phi-operands.ll | 5 ++---
llvm/test/Transforms/InstCombine/binop-select.ll | 2 +-
.../test/Transforms/InstCombine/dont-distribute-phi.ll | 10 ++++------
llvm/test/Transforms/InstCombine/fmul.ll | 4 ++--
llvm/test/Transforms/InstCombine/free-inversion.ll | 4 ++--
llvm/test/Transforms/InstCombine/recurrence.ll | 4 ++--
llvm/test/Transforms/InstCombine/sub-gep.ll | 3 +--
8 files changed, 16 insertions(+), 21 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 67f837c7ed968..391b6fd6ea083 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2261,11 +2261,10 @@ Instruction *InstCombinerImpl::foldBinopWithPhiOperands(BinaryOperator &BO) {
}
Instruction *InstCombinerImpl::foldBinOpIntoSelectOrPhi(BinaryOperator &I) {
- if (!isa<Constant>(I.getOperand(1)))
- return nullptr;
+ bool IsOtherParamConst = isa<Constant>(I.getOperand(1));
if (auto *Sel = dyn_cast<SelectInst>(I.getOperand(0))) {
- if (Instruction *NewSel = FoldOpIntoSelect(I, Sel))
+ if (Instruction *NewSel = FoldOpIntoSelect(I, Sel, false, !IsOtherParamConst))
return NewSel;
} else if (auto *PN = dyn_cast<PHINode>(I.getOperand(0))) {
if (Instruction *NewPhi = foldOpIntoPhi(I, PN))
diff --git a/llvm/test/Transforms/InstCombine/binop-phi-operands.ll b/llvm/test/Transforms/InstCombine/binop-phi-operands.ll
index 9e049837b0352..f0d4ad74fbe05 100644
--- a/llvm/test/Transforms/InstCombine/binop-phi-operands.ll
+++ b/llvm/test/Transforms/InstCombine/binop-phi-operands.ll
@@ -653,12 +653,11 @@ define i8 @mul_const_incoming0_speculatable(i1 %b, i8 %x, i8 %y) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[B:%.*]], label [[IF:%.*]], label [[THEN:%.*]]
; CHECK: if:
+; CHECK-NEXT: [[TMP0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br label [[THEN]]
; CHECK: then:
-; CHECK-NEXT: [[P0:%.*]] = phi i8 [ 42, [[ENTRY:%.*]] ], [ [[X:%.*]], [[IF]] ]
-; CHECK-NEXT: [[P1:%.*]] = phi i8 [ 17, [[ENTRY]] ], [ [[Y:%.*]], [[IF]] ]
+; CHECK-NEXT: [[R:%.*]] = phi i8 [ -54, [[ENTRY:%.*]] ], [ [[TMP0]], [[IF]] ]
; CHECK-NEXT: call void @sideeffect()
-; CHECK-NEXT: [[R:%.*]] = mul i8 [[P0]], [[P1]]
; CHECK-NEXT: ret i8 [[R]]
;
entry:
diff --git a/llvm/test/Transforms/InstCombine/binop-select.ll b/llvm/test/Transforms/InstCombine/binop-select.ll
index 25f624ee13412..002ff65c39f8c 100644
--- a/llvm/test/Transforms/InstCombine/binop-select.ll
+++ b/llvm/test/Transforms/InstCombine/binop-select.ll
@@ -335,7 +335,7 @@ define i32 @sub_sel_op1_use(i1 %b) {
define float @fadd_sel_op0(i1 %b, float %x) {
; CHECK-LABEL: @fadd_sel_op0(
-; CHECK-NEXT: [[R:%.*]] = select nnan i1 [[B:%.*]], float 0xFFF0000000000000, float 0x7FF0000000000000
+; CHECK-NEXT: [[R:%.*]] = select i1 [[B:%.*]], float 0xFFF0000000000000, float 0x7FF0000000000000
; CHECK-NEXT: ret float [[R]]
;
%s = select i1 %b, float 0xFFF0000000000000, float 0x7FF0000000000000
diff --git a/llvm/test/Transforms/InstCombine/dont-distribute-phi.ll b/llvm/test/Transforms/InstCombine/dont-distribute-phi.ll
index 45e47d8e781be..5e90d4b8d4419 100644
--- a/llvm/test/Transforms/InstCombine/dont-distribute-phi.ll
+++ b/llvm/test/Transforms/InstCombine/dont-distribute-phi.ll
@@ -7,7 +7,7 @@
define zeroext i1 @foo(i32 %arg) {
; CHECK-LABEL: @foo(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[ARG:%.*]], 37
+; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[ARG:%.*]], 37
; CHECK-NEXT: br i1 [[CMP1]], label [[BB_ELSE:%.*]], label [[BB_THEN:%.*]]
; CHECK: bb_then:
; CHECK-NEXT: call void @bar()
@@ -16,8 +16,7 @@ define zeroext i1 @foo(i32 %arg) {
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[ARG]], 17
; CHECK-NEXT: br label [[BB_EXIT]]
; CHECK: bb_exit:
-; CHECK-NEXT: [[PHI1:%.*]] = phi i1 [ [[CMP2]], [[BB_ELSE]] ], [ undef, [[BB_THEN]] ]
-; CHECK-NEXT: [[AND1:%.*]] = and i1 [[PHI1]], [[CMP1]]
+; CHECK-NEXT: [[AND1:%.*]] = phi i1 [ [[CMP2]], [[BB_THEN]] ], [ false, [[BB_ELSE]] ]
; CHECK-NEXT: ret i1 [[AND1]]
;
@@ -43,7 +42,7 @@ bb_exit:
define zeroext i1 @foo_logical(i32 %arg) {
; CHECK-LABEL: @foo_logical(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[ARG:%.*]], 37
+; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[ARG:%.*]], 37
; CHECK-NEXT: br i1 [[CMP1]], label [[BB_ELSE:%.*]], label [[BB_THEN:%.*]]
; CHECK: bb_then:
; CHECK-NEXT: call void @bar()
@@ -52,8 +51,7 @@ define zeroext i1 @foo_logical(i32 %arg) {
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[ARG]], 17
; CHECK-NEXT: br label [[BB_EXIT]]
; CHECK: bb_exit:
-; CHECK-NEXT: [[PHI1:%.*]] = phi i1 [ [[CMP2]], [[BB_ELSE]] ], [ undef, [[BB_THEN]] ]
-; CHECK-NEXT: [[AND1:%.*]] = and i1 [[PHI1]], [[CMP1]]
+; CHECK-NEXT: [[AND1:%.*]] = phi i1 [ [[CMP2]], [[BB_THEN]] ], [ false, [[BB_ELSE]] ]
; CHECK-NEXT: ret i1 [[AND1]]
;
diff --git a/llvm/test/Transforms/InstCombine/fmul.ll b/llvm/test/Transforms/InstCombine/fmul.ll
index cd4a8e36c6e23..3cbf7090a13b8 100644
--- a/llvm/test/Transforms/InstCombine/fmul.ll
+++ b/llvm/test/Transforms/InstCombine/fmul.ll
@@ -1222,7 +1222,7 @@ define <2 x double> @negate_if_true_wrong_constant(<2 x double> %px, i1 %cond) {
; X *fast (C ? 1.0 : 0.0) -> C ? X : 0.0
define float @fmul_select(float %x, i1 %c) {
; CHECK-LABEL: @fmul_select(
-; CHECK-NEXT: [[MUL:%.*]] = select fast i1 [[C:%.*]], float [[X:%.*]], float 0.000000e+00
+; CHECK-NEXT: [[MUL:%.*]] = select i1 [[C:%.*]], float [[X:%.*]], float 0.000000e+00
; CHECK-NEXT: ret float [[MUL]]
;
%sel = select i1 %c, float 1.0, float 0.0
@@ -1233,7 +1233,7 @@ define float @fmul_select(float %x, i1 %c) {
; X *fast (C ? 1.0 : 0.0) -> C ? X : 0.0
define <2 x float> @fmul_select_vec(<2 x float> %x, i1 %c) {
; CHECK-LABEL: @fmul_select_vec(
-; CHECK-NEXT: [[MUL:%.*]] = select fast i1 [[C:%.*]], <2 x float> [[X:%.*]], <2 x float> zeroinitializer
+; CHECK-NEXT: [[MUL:%.*]] = select i1 [[C:%.*]], <2 x float> [[X:%.*]], <2 x float> zeroinitializer
; CHECK-NEXT: ret <2 x float> [[MUL]]
;
%sel = select i1 %c, <2 x float> <float 1.0, float 1.0>, <2 x float> zeroinitializer
diff --git a/llvm/test/Transforms/InstCombine/free-inversion.ll b/llvm/test/Transforms/InstCombine/free-inversion.ll
index 4b69a5e77b4ce..2e8e75c3ab3ef 100644
--- a/llvm/test/Transforms/InstCombine/free-inversion.ll
+++ b/llvm/test/Transforms/InstCombine/free-inversion.ll
@@ -563,10 +563,10 @@ define i1 @test_inv_free(i1 %c1, i1 %c2, i1 %c3, i1 %c4) {
; CHECK: b2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: b3:
+; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[C3:%.*]], [[C4:%.*]]
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
-; CHECK-NEXT: [[VAL_NOT:%.*]] = phi i1 [ false, [[B1]] ], [ true, [[B2]] ], [ [[C3:%.*]], [[B3]] ]
-; CHECK-NEXT: [[COND_NOT:%.*]] = and i1 [[VAL_NOT]], [[C4:%.*]]
+; CHECK-NEXT: [[COND_NOT:%.*]] = phi i1 [ false, [[B1]] ], [ [[C4]], [[B2]] ], [ [[TMP0]], [[B3]] ]
; CHECK-NEXT: br i1 [[COND_NOT]], label [[B5:%.*]], label [[B4:%.*]]
; CHECK: b4:
; CHECK-NEXT: ret i1 true
diff --git a/llvm/test/Transforms/InstCombine/recurrence.ll b/llvm/test/Transforms/InstCombine/recurrence.ll
index f75e0d439c572..643e7efc243a3 100644
--- a/llvm/test/Transforms/InstCombine/recurrence.ll
+++ b/llvm/test/Transforms/InstCombine/recurrence.ll
@@ -24,9 +24,9 @@ loop: ; preds = %loop, %entry
define i64 @test_or2(i64 %a, i64 %b) {
; CHECK-LABEL: @test_or2(
; CHECK-NEXT: entry:
+; CHECK-NEXT: [[IV_NEXT:%.*]] = or i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
-; CHECK-NEXT: [[IV_NEXT:%.*]] = or i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: tail call void @use(i64 [[IV_NEXT]])
; CHECK-NEXT: br label [[LOOP]]
;
@@ -104,9 +104,9 @@ loop: ; preds = %loop, %entry
define i64 @test_and2(i64 %a, i64 %b) {
; CHECK-LABEL: @test_and2(
; CHECK-NEXT: entry:
+; CHECK-NEXT: [[IV_NEXT:%.*]] = and i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
-; CHECK-NEXT: [[IV_NEXT:%.*]] = and i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: tail call void @use(i64 [[IV_NEXT]])
; CHECK-NEXT: br label [[LOOP]]
;
diff --git a/llvm/test/Transforms/InstCombine/sub-gep.ll b/llvm/test/Transforms/InstCombine/sub-gep.ll
index ee70137e8fbd7..01da63fa5b0af 100644
--- a/llvm/test/Transforms/InstCombine/sub-gep.ll
+++ b/llvm/test/Transforms/InstCombine/sub-gep.ll
@@ -858,8 +858,7 @@ define i1 @_gep_phi2(ptr %str1, i64 %val2) {
; CHECK: while.end.i:
; CHECK-NEXT: br label [[_Z3FOOPKC_EXIT]]
; CHECK: _Z3fooPKc.exit:
-; CHECK-NEXT: [[RETVAL_0_I:%.*]] = phi i64 [ 1, [[WHILE_END_I]] ], [ 0, [[LOR_LHS_FALSE_I]] ], [ 0, [[ENTRY:%.*]] ]
-; CHECK-NEXT: [[TMP2:%.*]] = or i64 [[RETVAL_0_I]], [[VAL2:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = phi i64 [ 1, [[WHILE_END_I]] ], [ [[VAL2:%.*]], [[LOR_LHS_FALSE_I]] ], [ [[VAL2]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i64 [[TMP2]], 0
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
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