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llvm-project/llvm/test/Transforms/InstSimplify/domcondition.ll
Yingwei Zheng ca5ece8939
[InstSimplify] Simplify fcmp implied by dominating fcmp (#161090) 
This patch simplifies an fcmp into true/false if it is implied by a
dominating fcmp.
As an initial support, it only handles two cases:
+ `fcmp pred1, X, Y -> fcmp pred2, X, Y`: use set operations.
+ `fcmp pred1, X, C1 -> fcmp pred2, X, C2`: use `ConstantFPRange` and
set operations.

Note: It doesn't fix https://github.com/llvm/llvm-project/issues/70985,
as the second fcmp in the motivating case is not dominated by the edge.
We may need to adjust JumpThreading to handle this case.

Comptime impact (~+0.1%):
https://llvm-compile-time-tracker.com/compare.php?from=a728f213c863e4dd19f8969a417148d2951323c0&to=8ca70404fb0d66a824f39d83050ac38e2f1b25b9&stat=instructions:u
IR diff: https://github.com/dtcxzyw/llvm-opt-benchmark/pull/2848
2025-10-05 16:15:51 +08:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
define i32 @xor_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @xor_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: ret i32 0
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%xor = xor i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %xor, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @sub_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @sub_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: ret i32 0
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%sub = sub i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %sub, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @udiv_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @udiv_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ 1, [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%udiv = udiv i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %udiv, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @sdiv_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @sdiv_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ 1, [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%sdiv = sdiv i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %sdiv, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @urem_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @urem_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: ret i32 0
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%urem = urem i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %urem, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @srem_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @srem_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: ret i32 0
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%srem = srem i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %srem, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
; TODO: %and can be one of %x, %y
define i32 @and_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @and_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ [[Y]], [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%and = and i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %and, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
; TODO: %or can be one of %x, %y
define i32 @or_domcondition(i32 %x, i32 %y) {
; CHECK-LABEL: @or_domcondition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ [[Y]], [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%or = or i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %or, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
; negative test, dominate condtion is not eq
define i32 @xor_domcondition_negative(i32 %x, i32 %y) {
; CHECK-LABEL: @xor_domcondition_negative(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp uge i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[X]], [[Y]]
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ [[XOR]], [[COND_TRUE]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp uge i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
%xor = xor i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %xor, %cond.true ], [ 0, %entry ]
ret i32 %cond
}
define i32 @xor_simplify_by_dci(i32 %x, i32 %y, i1 %c) {
; CHECK-LABEL: @xor_simplify_by_dci(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[COND_TRUE:%.*]], label [[COND_END:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br i1 [[C:%.*]], label [[XORBB:%.*]], label [[COND_END]]
; CHECK: xorbb:
; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[X]], [[Y]]
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ [[XOR]], [[XORBB]] ], [ 0, [[ENTRY:%.*]] ], [ 0, [[COND_TRUE]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%cmp = icmp eq i32 %x, %y
br i1 %cmp, label %cond.true, label %cond.end
cond.true:
br i1 %c, label %xorbb, label %cond.end
xorbb:
%xor = xor i32 %x, %y
br label %cond.end
cond.end:
%cond = phi i32 [ %xor, %xorbb ], [ 0, %entry ], [0, %cond.true]
ret i32 %cond
}
define void @icmp_simplify_by_dci(i32 %a, i32 %b, i1 %x) {
; CHECK-LABEL: @icmp_simplify_by_dci(
; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: br i1 [[CMP1]], label [[END:%.*]], label [[TAKEN:%.*]]
; CHECK: taken:
; CHECK-NEXT: br i1 [[X:%.*]], label [[SELBB:%.*]], label [[END]]
; CHECK: selbb:
; CHECK-NEXT: [[CMP2:%.*]] = icmp ne i32 [[A]], [[B]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[CMP2]], i32 20, i32 0
; CHECK-NEXT: call void @foo(i32 [[C]])
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: ret void
;
%cmp1 = icmp eq i32 %a, %b
br i1 %cmp1, label %end, label %taken
taken:
br i1 %x, label %selbb, label %end
selbb:
%cmp2 = icmp ne i32 %a, %b
%c = select i1 %cmp2, i32 20, i32 0
call void @foo(i32 %c)
br label %end
end:
ret void
}
declare void @foo(i32)
define i1 @simplify_fcmp_implied_by_dom_cond_range_true(float %x) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_range_true(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 true
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, 0.0
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp olt float %x, 1.0
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_in_else_implied_by_dom_cond_range_true(float %x) {
; CHECK-LABEL: @simplify_fcmp_in_else_implied_by_dom_cond_range_true(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 true
; CHECK: if.else:
; CHECK-NEXT: ret i1 true
;
%cmp = fcmp olt float %x, 1.0
br i1 %cmp, label %if.then, label %if.else
if.then:
ret i1 true
if.else:
%cmp2 = fcmp uge float %x, 0.5
ret i1 %cmp2
}
define i1 @simplify_fcmp_implied_by_dom_cond_range_false(float %x) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_range_false(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 false
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, 0.0
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp ogt float %x, 1.0
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_pred_true(float %x, float %y) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_pred_true(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 true
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, %y
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp ole float %x, %y
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_pred_false(float %x, float %y) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_pred_false(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 false
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, %y
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp ogt float %x, %y
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_pred_commuted(float %x, float %y) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_pred_commuted(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: ret i1 true
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, %y
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp oge float %y, %x
ret i1 %cmp2
if.else:
ret i1 false
}
; Negative tests
define i1 @simplify_fcmp_implied_by_dom_cond_wrong_range(float %x) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_wrong_range(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[CMP2:%.*]] = fcmp olt float [[X]], -1.000000e+00
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, 0.0
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp olt float %x, -1.0
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_range_mismatched_operand(float %x, float %y) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_range_mismatched_operand(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[CMP2:%.*]] = fcmp olt float [[Y:%.*]], 1.000000e+00
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, 0.0
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp olt float %y, 1.0
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_wrong_pred(float %x, float %y) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_wrong_pred(
; CHECK-NEXT: [[CMP:%.*]] = fcmp ole float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[CMP2:%.*]] = fcmp olt float [[X]], [[Y]]
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp ole float %x, %y
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp olt float %x, %y
ret i1 %cmp2
if.else:
ret i1 false
}
define i1 @simplify_fcmp_implied_by_dom_cond_pred_mismatched_operand(float %x, float %y, float %z) {
; CHECK-LABEL: @simplify_fcmp_implied_by_dom_cond_pred_mismatched_operand(
; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[CMP2:%.*]] = fcmp ole float [[X]], [[Z:%.*]]
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: if.else:
; CHECK-NEXT: ret i1 false
;
%cmp = fcmp olt float %x, %y
br i1 %cmp, label %if.then, label %if.else
if.then:
%cmp2 = fcmp ole float %x, %z
ret i1 %cmp2
if.else:
ret i1 false
}
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