[llvm] [InstCombine] Missing optimization: fold mul (select a, b), (select b, a) to mul a, b (PR #74953)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,1117 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -passes=instcombine -S < %s | FileCheck %s
+
+declare float @llvm.maxnum.f32(float %a, float %b)
+declare float @llvm.minnum.f32(float %a, float %b)
+declare float @llvm.maximum.f32(float %a, float %b)
+declare float @llvm.minimum.f32(float %a, float %b)
+declare i32 @llvm.smax.i32(i32 %a, i32 %b)
+declare i32 @llvm.smin.i32(i32 %a, i32 %b)
+declare i32 @llvm.umax.i32(i32 %a, i32 %b)
+declare i32 @llvm.umin.i32(i32 %a, i32 %b)
+declare i16 @llvm.sadd.sat.i16(i16 %a, i16 %b)
+declare i16 @llvm.uadd.sat.i16(i16 %a, i16 %b)
+declare {i16, i1} @llvm.sadd.with.overflow.i16(i16 %a, i16 %b)
+declare {i16, i1} @llvm.uadd.with.overflow.i16(i16 %a, i16 %b)
+declare {i16, i1} @llvm.smul.with.overflow.i16(i16 %a, i16 %b)
+declare {i16, i1} @llvm.umul.with.overflow.i16(i16 %a, i16 %b)
+declare i16 @llvm.smul.fix.i16(i16 %a, i16 %b, i32 %scale)
+declare i16 @llvm.umul.fix.i16(i16 %a, i16 %b, i32 %scale)
+declare i16 @llvm.smul.fix.sat.i16(i16 %a, i16 %b, i32 %scale)
+declare i16 @llvm.umul.fix.sat.i16(i16 %a, i16 %b, i32 %scale)
+declare float @llvm.fma.f32(float %a, float %b, float %c)
+declare float @llvm.fmuladd.f32(float %a, float %b, float %c)
+
+define i8 @fold_select_mul(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_mul(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = mul i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = mul i8 %s1, %s0
+  ret i8 %ret
+}
+
+define i8 @fold_select_mul_nsw_nuw_preserve(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_mul_nsw_nuw_preserve(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = mul nuw nsw i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = mul nsw nuw i8 %s1, %s0
+  ret i8 %ret
+}
+
+define <2 x i4> @fold_select_mul_vec2(i1 %c, <2 x i4> %a, <2 x i4> %b) {
+; CHECK-LABEL: define <2 x i4> @fold_select_mul_vec2(
+; CHECK-SAME: i1 [[C:%.*]], <2 x i4> [[A:%.*]], <2 x i4> [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = mul <2 x i4> [[B]], [[A]]
+; CHECK-NEXT:    ret <2 x i4> [[RET]]
+;
+  %s0 = select i1 %c, <2 x i4> %a, <2 x i4> %b
+  %s1 = select i1 %c, <2 x i4> %b, <2 x i4> %a
+  %ret = mul <2 x i4> %s1, %s0
+  ret <2 x i4> %ret
+}
+
+define i8 @fold_select_add(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_add(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = add i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = add i8 %s1, %s0
+  ret i8 %ret
+}
+
+define <2 x i4> @fold_select_add_vec2(i1 %c, <2 x i4> %a, <2 x i4> %b) {
+; CHECK-LABEL: define <2 x i4> @fold_select_add_vec2(
+; CHECK-SAME: i1 [[C:%.*]], <2 x i4> [[A:%.*]], <2 x i4> [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = add <2 x i4> [[B]], [[A]]
+; CHECK-NEXT:    ret <2 x i4> [[RET]]
+;
+  %s0 = select i1 %c, <2 x i4> %a, <2 x i4> %b
+  %s1 = select i1 %c, <2 x i4> %b, <2 x i4> %a
+  %ret = add <2 x i4> %s1, %s0
+  ret <2 x i4> %ret
+}
+
+define i8 @fold_select_and(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_and(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = and i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = and i8 %s1, %s0
+  ret i8 %ret
+}
+
+define <2 x i4> @fold_select_and_vec2(i1 %c, <2 x i4> %a, <2 x i4> %b) {
+; CHECK-LABEL: define <2 x i4> @fold_select_and_vec2(
+; CHECK-SAME: i1 [[C:%.*]], <2 x i4> [[A:%.*]], <2 x i4> [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = and <2 x i4> [[B]], [[A]]
+; CHECK-NEXT:    ret <2 x i4> [[RET]]
+;
+  %s0 = select i1 %c, <2 x i4> %a, <2 x i4> %b
+  %s1 = select i1 %c, <2 x i4> %b, <2 x i4> %a
+  %ret = and <2 x i4> %s1, %s0
+  ret <2 x i4> %ret
+}
+
+define i8 @fold_select_or(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_or(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = or i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = or i8 %s1, %s0
+  ret i8 %ret
+}
+
+define <2 x i4> @fold_select_or_vec2(i1 %c, <2 x i4> %a, <2 x i4> %b) {
+; CHECK-LABEL: define <2 x i4> @fold_select_or_vec2(
+; CHECK-SAME: i1 [[C:%.*]], <2 x i4> [[A:%.*]], <2 x i4> [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = or <2 x i4> [[B]], [[A]]
+; CHECK-NEXT:    ret <2 x i4> [[RET]]
+;
+  %s0 = select i1 %c, <2 x i4> %a, <2 x i4> %b
+  %s1 = select i1 %c, <2 x i4> %b, <2 x i4> %a
+  %ret = or <2 x i4> %s1, %s0
+  ret <2 x i4> %ret
+}
+
+define i8 @fold_select_xor(i1 %c, i8 %a, i8 %b) {
+; CHECK-LABEL: define i8 @fold_select_xor(
+; CHECK-SAME: i1 [[C:%.*]], i8 [[A:%.*]], i8 [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = xor i8 [[B]], [[A]]
+; CHECK-NEXT:    ret i8 [[RET]]
+;
+  %s0 = select i1 %c, i8 %a, i8 %b
+  %s1 = select i1 %c, i8 %b, i8 %a
+  %ret = xor i8 %s1, %s0
+  ret i8 %ret
+}
+
+define <2 x i4> @fold_select_xor_vec2(i1 %c, <2 x i4> %a, <2 x i4> %b) {
+; CHECK-LABEL: define <2 x i4> @fold_select_xor_vec2(
+; CHECK-SAME: i1 [[C:%.*]], <2 x i4> [[A:%.*]], <2 x i4> [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = xor <2 x i4> [[B]], [[A]]
+; CHECK-NEXT:    ret <2 x i4> [[RET]]
+;
+  %s0 = select i1 %c, <2 x i4> %a, <2 x i4> %b
+  %s1 = select i1 %c, <2 x i4> %b, <2 x i4> %a
+  %ret = xor <2 x i4> %s1, %s0
+  ret <2 x i4> %ret
+}
+
+define float @fold_select_fadd(i1 %c, float %a, float %b) {
+; CHECK-LABEL: define float @fold_select_fadd(
+; CHECK-SAME: i1 [[C:%.*]], float [[A:%.*]], float [[B:%.*]]) {
+; CHECK-NEXT:    [[RET:%.*]] = fadd float [[B]], [[A]]
+; CHECK-NEXT:    ret float [[RET]]
+;
+  %s0 = select i1 %c, float %a, float %b
+  %s1 = select i1 %c, float %b, float %a
+  %ret = fadd float %s1, %s0
----------------
nikic wrote:

Add `nnan` here to test FMF preservation.

https://github.com/llvm/llvm-project/pull/74953