[InstCombine] Replace all dominated uses of condition with constants #105510
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesThis patch replaces all dominated uses of condition with true/false to improve context-sensitive optimizations. It eliminates a bunch of branches in llvm-opt-benchmark. As a side effect, it may introduce new phi nodes in some corner cases. See the following case: It will be simplified into: I am planning to fix this in late pipeline/CGP since this problem exists before the patch. Patch is 25.93 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/105510.diff 15 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 8a96d1d0fb4c90..6328241e35a5b2 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3705,6 +3705,20 @@ Instruction *InstCombinerImpl::visitBranchInst(BranchInst &BI) {
return nullptr;
}
+ // Replace all dominated uses of the condition with true/false
+ if (BI.getSuccessor(0) != BI.getSuccessor(1)) {
+ for (auto &U : make_early_inc_range(Cond->uses())) {
+ BasicBlockEdge Edge0(BI.getParent(), BI.getSuccessor(0));
+ if (DT.dominates(Edge0, U)) {
+ replaceUse(U, ConstantInt::getTrue(Cond->getType()));
+ continue;
+ }
+ BasicBlockEdge Edge1(BI.getParent(), BI.getSuccessor(1));
+ if (DT.dominates(Edge1, U))
+ replaceUse(U, ConstantInt::getFalse(Cond->getType()));
+ }
+ }
+
DC.registerBranch(&BI);
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
index 474da9968b66ad..a728c294628cad 100644
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -485,7 +485,7 @@ define i1 @nonnull3B(ptr %a, i1 %control) {
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]]) [ "nonnull"(ptr [[LOAD]]) ]
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK: not_taken:
-; CHECK-NEXT: ret i1 [[CONTROL]]
+; CHECK-NEXT: ret i1 false
;
entry:
%load = load ptr, ptr %a
@@ -513,7 +513,7 @@ define i1 @nonnull3C(ptr %a, i1 %control) {
; CHECK: exit:
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: not_taken:
-; CHECK-NEXT: ret i1 [[CONTROL]]
+; CHECK-NEXT: ret i1 false
;
entry:
%load = load ptr, ptr %a
@@ -543,7 +543,7 @@ define i1 @nonnull3D(ptr %a, i1 %control) {
; CHECK: exit:
; CHECK-NEXT: ret i1 [[CMP2]]
; CHECK: not_taken:
-; CHECK-NEXT: ret i1 [[CONTROL]]
+; CHECK-NEXT: ret i1 false
;
entry:
%load = load ptr, ptr %a
diff --git a/llvm/test/Transforms/InstCombine/branch.ll b/llvm/test/Transforms/InstCombine/branch.ll
index 1110d5f90b1790..1d5ff72eef9ce6 100644
--- a/llvm/test/Transforms/InstCombine/branch.ll
+++ b/llvm/test/Transforms/InstCombine/branch.ll
@@ -242,3 +242,99 @@ t:
f:
ret i32 3
}
+
+define i32 @dom_true(i1 %cmp) {
+; CHECK-LABEL: @dom_true(
+; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: ret i32 1
+; CHECK: if.else:
+; CHECK-NEXT: ret i32 0
+;
+ br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+ %zext = zext i1 %cmp to i32
+ ret i32 %zext
+
+if.else:
+ ret i32 0
+}
+
+define i32 @dom_false(i1 %cmp) {
+; CHECK-LABEL: @dom_false(
+; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF_ELSE:%.*]], label [[IF_THEN:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: ret i32 0
+; CHECK: if.else:
+; CHECK-NEXT: ret i32 0
+;
+ br i1 %cmp, label %if.else, label %if.then
+
+if.then:
+ %zext = zext i1 %cmp to i32
+ ret i32 %zext
+
+if.else:
+ ret i32 0
+}
+
+define i32 @dom_true_phi(i1 %cmp) {
+; CHECK-LABEL: @dom_true_phi(
+; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: br label [[IF_END:%.*]]
+; CHECK: if.else:
+; CHECK-NEXT: br label [[IF_END]]
+; CHECK: if.end:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT: ret i32 [[ZEXT]]
+;
+ br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+ br label %if.end
+
+if.else:
+ br label %if.end
+
+if.end:
+ %phi = phi i1 [ true, %if.then ], [ %cmp, %if.else ]
+ %zext = zext i1 %phi to i32
+ ret i32 %zext
+}
+
+; Negative tests
+
+define i32 @same_dest(i1 %cmp) {
+; CHECK-LABEL: @same_dest(
+; CHECK-NEXT: br i1 false, label [[IF_THEN:%.*]], label [[IF_THEN]]
+; CHECK: if.then:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i1 [[CMP:%.*]] to i32
+; CHECK-NEXT: ret i32 [[ZEXT]]
+;
+ br i1 %cmp, label %if.then, label %if.then
+
+if.then:
+ %zext = zext i1 %cmp to i32
+ ret i32 %zext
+}
+
+define i32 @not_dom(i1 %cmp) {
+; CHECK-LABEL: @not_dom(
+; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: br label [[IF_ELSE]]
+; CHECK: if.else:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT: ret i32 [[ZEXT]]
+;
+ br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+ br label %if.else
+
+if.else:
+ %zext = zext i1 %cmp to i32
+ ret i32 %zext
+}
diff --git a/llvm/test/Transforms/InstCombine/compare-unescaped.ll b/llvm/test/Transforms/InstCombine/compare-unescaped.ll
index ab380c00f82641..02eb464c814c81 100644
--- a/llvm/test/Transforms/InstCombine/compare-unescaped.ll
+++ b/llvm/test/Transforms/InstCombine/compare-unescaped.ll
@@ -86,7 +86,7 @@ define i1 @compare_and_call_after() {
; CHECK-NEXT: call void @escape(ptr [[M]])
; CHECK-NEXT: ret i1 true
; CHECK: just_return:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%m = call ptr @malloc(i64 24)
%lgp = load ptr, ptr @gp, align 8, !nonnull !0
diff --git a/llvm/test/Transforms/InstCombine/icmp-dom.ll b/llvm/test/Transforms/InstCombine/icmp-dom.ll
index 83cedd5ea9cb45..3cf3a7af77041c 100644
--- a/llvm/test/Transforms/InstCombine/icmp-dom.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-dom.ll
@@ -196,7 +196,7 @@ define i1 @trueblock_cmp_is_false(i32 %x, i32 %y) {
; CHECK: t:
; CHECK-NEXT: ret i1 false
; CHECK: f:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
entry:
%cmp = icmp sgt i32 %x, %y
@@ -216,7 +216,7 @@ define i1 @trueblock_cmp_is_false_commute(i32 %x, i32 %y) {
; CHECK: t:
; CHECK-NEXT: ret i1 false
; CHECK: f:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
entry:
%cmp = icmp eq i32 %x, %y
@@ -236,7 +236,7 @@ define i1 @trueblock_cmp_is_true(i32 %x, i32 %y) {
; CHECK: t:
; CHECK-NEXT: ret i1 true
; CHECK: f:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
entry:
%cmp = icmp ult i32 %x, %y
@@ -256,7 +256,7 @@ define i1 @trueblock_cmp_is_true_commute(i32 %x, i32 %y) {
; CHECK: t:
; CHECK-NEXT: ret i1 true
; CHECK: f:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
entry:
%cmp = icmp ugt i32 %x, %y
@@ -271,10 +271,10 @@ f:
define i1 @falseblock_cmp_is_false(i32 %x, i32 %y) {
; CHECK-LABEL: @falseblock_cmp_is_false(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[CMP:%.*]] = icmp sle i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
+; CHECK-NEXT: [[CMP_NOT:%.*]] = icmp sgt i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[CMP_NOT]], label [[F:%.*]], label [[T:%.*]]
; CHECK: t:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
; CHECK: f:
; CHECK-NEXT: ret i1 false
;
@@ -294,7 +294,7 @@ define i1 @falseblock_cmp_is_false_commute(i32 %x, i32 %y) {
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
; CHECK: t:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
; CHECK: f:
; CHECK-NEXT: ret i1 false
;
@@ -314,7 +314,7 @@ define i1 @falseblock_cmp_is_true(i32 %x, i32 %y) {
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
; CHECK: t:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
; CHECK: f:
; CHECK-NEXT: ret i1 true
;
@@ -334,7 +334,7 @@ define i1 @falseblock_cmp_is_true_commute(i32 %x, i32 %y) {
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
; CHECK: t:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
; CHECK: f:
; CHECK-NEXT: ret i1 true
;
diff --git a/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll b/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
index 2b5b3fce705354..ef8f5fea4ff7c1 100644
--- a/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
+++ b/llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
@@ -292,7 +292,7 @@ define i1 @test7() {
; CHECK-NEXT: [[CMP:%.*]] = phi i1 [ false, [[ENTRY:%.*]] ], [ true, [[BB7]] ]
; CHECK-NEXT: br i1 [[CMP]], label [[BB10:%.*]], label [[BB7]]
; CHECK: bb10:
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
entry:
br label %bb7
diff --git a/llvm/test/Transforms/InstCombine/known-bits.ll b/llvm/test/Transforms/InstCombine/known-bits.ll
index 3482a8e9759929..8cfb987e422f38 100644
--- a/llvm/test/Transforms/InstCombine/known-bits.ll
+++ b/llvm/test/Transforms/InstCombine/known-bits.ll
@@ -1664,11 +1664,9 @@ define i64 @pr92084(double %x) {
; CHECK-NEXT: [[CMP:%.*]] = fcmp uno double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN1:%.*]], label [[IF_ELSE:%.*]]
; CHECK: if.then1:
-; CHECK-NEXT: br i1 [[CMP]], label [[IF_ELSE]], label [[IF_THEN2:%.*]]
+; CHECK-NEXT: br i1 true, label [[IF_ELSE]], label [[IF_THEN2:%.*]]
; CHECK: if.then2:
-; CHECK-NEXT: [[CAST:%.*]] = bitcast double [[X]] to i64
-; CHECK-NEXT: [[AND:%.*]] = and i64 [[CAST]], 1
-; CHECK-NEXT: ret i64 [[AND]]
+; CHECK-NEXT: ret i64 poison
; CHECK: if.else:
; CHECK-NEXT: ret i64 0
;
diff --git a/llvm/test/Transforms/InstCombine/phi-known-bits-operand-order.ll b/llvm/test/Transforms/InstCombine/phi-known-bits-operand-order.ll
index a9ebcf629a4029..728ac7bd9fe411 100644
--- a/llvm/test/Transforms/InstCombine/phi-known-bits-operand-order.ll
+++ b/llvm/test/Transforms/InstCombine/phi-known-bits-operand-order.ll
@@ -11,14 +11,12 @@ define void @phi_recurrence_start_first() {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WHILE_COND:%.*]]
; CHECK: while.cond:
-; CHECK-NEXT: [[CELL_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[START:%.*]], [[FOR_COND26:%.*]] ]
; CHECK-NEXT: [[COND_V:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[COND_V]], label [[IF_THEN:%.*]], label [[WHILE_END:%.*]]
; CHECK: if.then:
-; CHECK-NEXT: [[START]] = add nuw nsw i32 [[CELL_0]], 1
-; CHECK-NEXT: br i1 [[COND_V]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
+; CHECK-NEXT: br i1 true, label [[FOR_COND11:%.*]], label [[FOR_COND26:%.*]]
; CHECK: for.cond11:
-; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[START]], [[IF_THEN]] ], [ [[STEP:%.*]], [[FOR_COND11]] ]
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ 1, [[IF_THEN]] ], [ [[STEP:%.*]], [[FOR_COND11]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
@@ -57,14 +55,12 @@ define void @phi_recurrence_step_first() {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WHILE_COND:%.*]]
; CHECK: while.cond:
-; CHECK-NEXT: [[CELL_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[START:%.*]], [[FOR_COND26:%.*]] ]
; CHECK-NEXT: [[COND_V:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[COND_V]], label [[IF_THEN:%.*]], label [[WHILE_END:%.*]]
; CHECK: if.then:
-; CHECK-NEXT: [[START]] = add nuw nsw i32 [[CELL_0]], 1
-; CHECK-NEXT: br i1 [[COND_V]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
+; CHECK-NEXT: br i1 true, label [[FOR_COND11:%.*]], label [[FOR_COND26:%.*]]
; CHECK: for.cond11:
-; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[STEP:%.*]], [[FOR_COND11]] ], [ [[START]], [[IF_THEN]] ]
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[STEP:%.*]], [[FOR_COND11]] ], [ 1, [[IF_THEN]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
diff --git a/llvm/test/Transforms/InstCombine/phi.ll b/llvm/test/Transforms/InstCombine/phi.ll
index 673c8f6c9488d6..ba29f4290a9fa4 100644
--- a/llvm/test/Transforms/InstCombine/phi.ll
+++ b/llvm/test/Transforms/InstCombine/phi.ll
@@ -1543,7 +1543,7 @@ define i1 @phi_knownnonzero_eq_multiuse_oricmp(i32 %n, i32 %s, ptr %P, i32 %val)
; CHECK-NEXT: [[BOOL2:%.*]] = icmp eq i32 [[PHI]], 0
; CHECK-NEXT: br label [[CLEANUP]]
; CHECK: cleanup:
-; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ [[CMP1]], [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
+; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ false, [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
; CHECK-NEXT: ret i1 [[FINAL]]
;
entry:
@@ -1581,13 +1581,13 @@ define i1 @phi_knownnonzero_ne_multiuse_oricmp_commuted(i32 %n, i32 %s, ptr %P,
; CHECK: if.end:
; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ 1, [[IF_THEN]] ], [ [[N]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[ORPHI:%.*]] = or i32 [[VAL:%.*]], [[PHI]]
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[ORPHI]], 0
-; CHECK-NEXT: br i1 [[CMP1]], label [[NEXT:%.*]], label [[CLEANUP:%.*]]
+; CHECK-NEXT: [[CMP1_NOT:%.*]] = icmp eq i32 [[ORPHI]], 0
+; CHECK-NEXT: br i1 [[CMP1_NOT]], label [[CLEANUP:%.*]], label [[NEXT:%.*]]
; CHECK: next:
; CHECK-NEXT: [[BOOL2:%.*]] = icmp ne i32 [[PHI]], 0
; CHECK-NEXT: br label [[CLEANUP]]
; CHECK: cleanup:
-; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ [[CMP1]], [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
+; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ false, [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
; CHECK-NEXT: ret i1 [[FINAL]]
;
entry:
@@ -1634,7 +1634,7 @@ define i1 @phi_knownnonzero_eq_multiuse_andicmp(i32 %n, i32 %s, ptr %P, i32 %val
; CHECK-NEXT: [[BOOL2:%.*]] = icmp eq i32 [[PHI]], 0
; CHECK-NEXT: br label [[CLEANUP]]
; CHECK: cleanup:
-; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ [[CMP1]], [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
+; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ false, [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
; CHECK-NEXT: ret i1 [[FINAL]]
;
entry:
@@ -1675,13 +1675,13 @@ define i1 @phi_knownnonzero_ne_multiuse_andicmp(i32 %n, i32 %s, ptr %P, i32 %val
; CHECK: if.end:
; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ [[SEL]], [[IF_THEN]] ], [ [[N]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[ANDPHI:%.*]] = and i32 [[PHI]], [[VAL:%.*]]
-; CHECK-NEXT: [[CMP1:%.*]] = icmp ne i32 [[ANDPHI]], 0
-; CHECK-NEXT: br i1 [[CMP1]], label [[NEXT:%.*]], label [[CLEANUP:%.*]]
+; CHECK-NEXT: [[CMP1_NOT:%.*]] = icmp eq i32 [[ANDPHI]], 0
+; CHECK-NEXT: br i1 [[CMP1_NOT]], label [[CLEANUP:%.*]], label [[NEXT:%.*]]
; CHECK: next:
; CHECK-NEXT: [[BOOL2:%.*]] = icmp ne i32 [[PHI]], 0
; CHECK-NEXT: br label [[CLEANUP]]
; CHECK: cleanup:
-; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ [[CMP1]], [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
+; CHECK-NEXT: [[FINAL:%.*]] = phi i1 [ false, [[IF_END]] ], [ [[BOOL2]], [[NEXT]] ]
; CHECK-NEXT: ret i1 [[FINAL]]
;
entry:
diff --git a/llvm/test/Transforms/InstCombine/pr44245.ll b/llvm/test/Transforms/InstCombine/pr44245.ll
index ee5ae2edb42dae..01f209c23592f7 100644
--- a/llvm/test/Transforms/InstCombine/pr44245.ll
+++ b/llvm/test/Transforms/InstCombine/pr44245.ll
@@ -8,54 +8,42 @@ define void @test(i1 %c, ptr %p) {
; CHECK-NEXT: bb16:
; CHECK-NEXT: br i1 [[C:%.*]], label [[BB17:%.*]], label [[BB24:%.*]]
; CHECK: bb17:
-; CHECK-NEXT: [[I:%.*]] = phi ptr [ [[DOTIN1:%.*]], [[BB47:%.*]] ], [ undef, [[BB16:%.*]] ]
-; CHECK-NEXT: store ptr [[I]], ptr [[P:%.*]], align 8
; CHECK-NEXT: ret void
; CHECK: bb24:
-; CHECK-NEXT: br i1 [[C]], label [[BB44:%.*]], label [[BB49:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB44:%.*]], label [[BB49:%.*]]
; CHECK: bb44:
-; CHECK-NEXT: [[TMP46:%.*]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
-; CHECK-NEXT: br label [[BB47]]
+; CHECK-NEXT: br label [[BB47:%.*]]
; CHECK: bb47:
-; CHECK-NEXT: [[DOTIN1]] = phi ptr [ [[DOTIN:%.*]], [[BB150:%.*]] ], [ [[TMP122:%.*]], [[BB119:%.*]] ], [ [[TMP103:%.*]], [[BB101:%.*]] ], [ [[TMP93:%.*]], [[BB91:%.*]] ], [ [[TMP83:%.*]], [[BB81:%.*]] ], [ [[TMP70:%.*]], [[BB67:%.*]] ], [ [[TMP58:%.*]], [[BB56:%.*]] ], [ [[TMP46]], [[BB44]] ]
; CHECK-NEXT: br label [[BB17]]
; CHECK: bb49:
-; CHECK-NEXT: br i1 [[C]], label [[BB56]], label [[BB59:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB56:%.*]], label [[BB59:%.*]]
; CHECK: bb56:
-; CHECK-NEXT: [[TMP58]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb59:
-; CHECK-NEXT: br i1 [[C]], label [[BB67]], label [[BB71:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB67:%.*]], label [[BB71:%.*]]
; CHECK: bb67:
-; CHECK-NEXT: [[TMP70]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb71:
-; CHECK-NEXT: br i1 [[C]], label [[BB81]], label [[BB84:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB81:%.*]], label [[BB84:%.*]]
; CHECK: bb81:
-; CHECK-NEXT: [[TMP83]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb84:
-; CHECK-NEXT: br i1 [[C]], label [[BB91]], label [[BB94:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB91:%.*]], label [[BB94:%.*]]
; CHECK: bb91:
-; CHECK-NEXT: [[TMP93]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb94:
-; CHECK-NEXT: br i1 [[C]], label [[BB101]], label [[BB104:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB101:%.*]], label [[BB104:%.*]]
; CHECK: bb101:
-; CHECK-NEXT: [[TMP103]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb104:
-; CHECK-NEXT: br i1 [[C]], label [[BB119]], label [[BB123:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB119:%.*]], label [[BB123:%.*]]
; CHECK: bb119:
-; CHECK-NEXT: [[TMP122]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb123:
-; CHECK-NEXT: br i1 [[C]], label [[BB147:%.*]], label [[BB152:%.*]]
+; CHECK-NEXT: br i1 false, label [[BB147:%.*]], label [[BB152:%.*]]
; CHECK: bb147:
-; CHECK-NEXT: [[TMP149:%.*]] = load ptr, ptr inttoptr (i64 16 to ptr), align 16
-; CHECK-NEXT: br label [[BB150]]
+; CHECK-NEXT: br label [[BB150:%.*]]
; CHECK: bb150:
-; CHECK-NEXT: [[DOTIN]] = phi ptr [ poison, [[BB152]] ], [ [[TMP149]], [[BB147]] ]
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb152:
; CHECK-NEXT: store i1 true, ptr poison, align 1
diff --git a/llvm/test/Transforms/InstCombine/sink-into-ncd.ll b/llvm/test/Transforms/InstCombine/sink-into-ncd.ll
index 464cc477a503c9..5fa692d3ae7288 100644
--- a/llvm/test/Transforms/InstCombine/sink-into-ncd.ll
+++ b/llvm/test/Transforms/InstCombine/sink-into-ncd.ll
@@ -60,12 +60,12 @@ define i32 @test2(ptr %addr, i1 %c) {
; CHECK-NEXT: br label [[EXIT]]
; CHECK: right:
; CHECK-NEXT: [[Y:%.*]] = call i32 @use(ptr [[PTR]])
-; CHECK-NEXT: br i1 [[C]], label [[EXIT]], label [[RIGHT_2:%.*]]
+; CHECK-NEXT: br i1 false, label [[EXIT]], label [[RIGHT_2:%.*]]
; CHECK: right.2:
; CHECK-NEXT: [[Z:%.*]] = call i32 @use(ptr [[PTR]])
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
-; CHECK-NEXT: [[P:%.*]] = phi i32 [ [[X]], [[LEFT]] ], [ [[Y]], [[RIGHT]] ], [ [[Z]], [[RIGHT_2]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT: [[P:%.*]] = phi i32 [ [[X]], [[LEFT]] ], [ poison, [[RIGHT]] ], [ [[Z]], [[RIGHT_2]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[P]]
;
entry:
diff --git a/llvm/test/Transforms/InstCombine/sink_to_unreachable.ll b/llvm/test/Transforms/InstCombine/sink_to_unreachable.ll
index 02ed22217854ea..922d372618e4d2 100644
--- a/llvm/test/Transforms/InstCombine/sink_to_unreachable.ll
+++ b/llvm/test/Transforms/InstCombine/sink_to_unreachable.ll
@@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -passes=instcombine -S < %s | FileCheck %s
+; RUN: opt -passes="instcombine<max-iterations=2>" -S < %s | FileCheck %s
declare void @use(i32 %x)
declare i1 @cond()
@@ -42,9 +42,8 @@ define void @test_02(i32 %x, i32 %y) {
; CHECK-NEXT: [[C3:%.*]] = icmp sgt i32 [[X]], [[Y]]
; CHECK-NEXT: br i1 [[C3]], label [[EXIT]], label [[UNREACHED:%.*]]
; CHECK: unreached:
-; CHECK-NEXT: [[C1:%.*]] = icmp eq i32 [[...
[truncated]
|
nikic
reviewed
Aug 26, 2024
| ; CHECK-NEXT: [[COND_V:%.*]] = call i1 @cond() | ||
| ; CHECK-NEXT: br i1 [[COND_V]], label [[IF_THEN:%.*]], label [[WHILE_END:%.*]] | ||
| ; CHECK: if.then: | ||
| ; CHECK-NEXT: [[START]] = add nuw nsw i32 [[CELL_0]], 1 | ||
| ; CHECK-NEXT: br i1 [[COND_V]], label [[FOR_COND11:%.*]], label [[FOR_COND26]] | ||
| ; CHECK-NEXT: br i1 true, label [[FOR_COND11:%.*]], label [[FOR_COND26:%.*]] |
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Same here and probably some other tests.
| @@ -1,5 +1,5 @@ | |||
| ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py | |||
| ; RUN: opt -passes=instcombine -S < %s | FileCheck %s | |||
| ; RUN: opt -passes="instcombine<max-iterations=2>" -S < %s | FileCheck %s | |||
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Add justification (and anywhere else the option is used).
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Addressed by adding the user to worklist.
|
It may be worthwhile to add a PhaseOrdering test that demonstrates why doing this in InstCombine is useful. |
goldsteinn
reviewed
Aug 26, 2024
| replaceUse(U, ConstantInt::getFalse(Cond->getType())); | ||
| } | ||
| } | ||
|
|
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Can we do the same thing with switches?
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See llvm/test/Transforms/PhaseOrdering/branch-dom-cond.ll. It is extracted from bullet3 (function |
nikic
approved these changes
Aug 31, 2024
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So the problem here is that GVN CSE's two icmps, but we only have the needed dominance relationship after JumpThreading. And after that we don't have passes capable of doing this anymore. So I think the InstCombine approach is fine.
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/123/builds/4693 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/141/builds/2024 Here is the relevant piece of the build log for the reference |
|
Hi @dtcxzyw I've bisected a problem back to this patch. It's very weird, when we iterate over the uses of the condition |
It is weird :) I will post a workaround patch later. |
dtcxzyw
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Oct 28, 2024
This patch skips constant expressions to avoid iterating over uses on other functions. Fix crash reported in #105510 (comment).
NoumanAmir657
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Nov 4, 2024
This patch skips constant expressions to avoid iterating over uses on other functions. Fix crash reported in llvm#105510 (comment).
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This patch replaces all dominated uses of condition with true/false to improve context-sensitive optimizations. It eliminates a bunch of branches in llvm-opt-benchmark.
As a side effect, it may introduce new phi nodes in some corner cases. See the following case:
It will be simplified into:
I am planning to fix this in late pipeline/CGP since this problem exists before the patch.