[llvm-commits] [llvm] r120323 - in /llvm/trunk: lib/Transforms/InstCombine/InstructionCombining.cpp test/Transforms/InstCombine/extractvalue.ll
Frits van Bommel
fvbommel at gmail.com
Mon Nov 29 13:56:20 PST 2010
Author: fvbommel
Date: Mon Nov 29 15:56:20 2010
New Revision: 120323
URL: http://llvm.org/viewvc/llvm-project?rev=120323&view=rev
Log:
Transform (extractvalue (load P), ...) to (load (gep P, 0, ...)) if the load has no other uses, shrinking the load.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/extractvalue.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=120323&r1=120322&r2=120323&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon Nov 29 15:56:20 2010
@@ -1171,10 +1171,37 @@
}
}
}
- // Can't simplify extracts from other values. Note that nested extracts are
- // already simplified implicitely by the above (extract ( extract (insert) )
+ if (LoadInst *L = dyn_cast<LoadInst>(Agg))
+ // If the (non-volatile) load only has one use, we can rewrite this to a
+ // load from a GEP. This reduces the size of the load.
+ // FIXME: If a load is used only by extractvalue instructions then this
+ // could be done regardless of having multiple uses.
+ if (!L->isVolatile() && L->hasOneUse()) {
+ // extractvalue has integer indices, getelementptr has Value*s. Convert.
+ SmallVector<Value*, 4> Indices;
+ // Prefix an i32 0 since we need the first element.
+ Indices.push_back(Builder->getInt32(0));
+ for (ExtractValueInst::idx_iterator I = EV.idx_begin(), E = EV.idx_end();
+ I != E; ++I)
+ Indices.push_back(Builder->getInt32(*I));
+
+ // We need to insert these at the location of the old load, not at that of
+ // the extractvalue.
+ Builder->SetInsertPoint(L->getParent(), L);
+ Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(),
+ Indices.begin(), Indices.end());
+ // Returning the load directly will cause the main loop to insert it in
+ // the wrong spot, so use ReplaceInstUsesWith().
+ return ReplaceInstUsesWith(EV, Builder->CreateLoad(GEP));
+ }
+ // We could simplify extracts from other values. Note that nested extracts may
+ // already be simplified implicitly by the above: extract (extract (insert) )
// will be translated into extract ( insert ( extract ) ) first and then just
- // the value inserted, if appropriate).
+ // the value inserted, if appropriate. Similarly for extracts from single-use
+ // loads: extract (extract (load)) will be translated to extract (load (gep))
+ // and if again single-use then via load (gep (gep)) to load (gep).
+ // However, double extracts from e.g. function arguments or return values
+ // aren't handled yet.
return 0;
}
Modified: llvm/trunk/test/Transforms/InstCombine/extractvalue.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/extractvalue.ll?rev=120323&r1=120322&r2=120323&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/extractvalue.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/extractvalue.ll Mon Nov 29 15:56:20 2010
@@ -1,10 +1,13 @@
-; RUN: opt < %s -instcombine -S | not grep extractvalue
+; RUN: opt < %s -instcombine -S | FileCheck %s
-; Instcombine should fold various combinations of insertvalue and extractvalue
-; together
declare void @bar({i32, i32} %a)
+declare i32 @baz(i32 %a)
+; CHECK: define i32 @foo
+; CHECK-NOT: extractvalue
define i32 @foo(i32 %a, i32 %b) {
+; Instcombine should fold various combinations of insertvalue and extractvalue
+; together
; Build a simple struct and pull values out again
%s1.1 = insertvalue {i32, i32} undef, i32 %a, 0
%s1 = insertvalue {i32, i32} %s1.1, i32 %b, 1
@@ -36,3 +39,69 @@
ret i32 %v5
}
+; CHECK: define i32 @extract2gep
+; CHECK-NEXT: [[GEP:%[a-z0-9]+]] = getelementptr inbounds {{.*}}* %pair, i32 0, i32 1
+; CHECK-NEXT: [[LOAD:%[A-Za-z0-9]+]] = load i32* [[GEP]]
+; CHECK-NEXT: store
+; CHECK-NEXT: br label %loop
+; CHECK-NOT: extractvalue
+; CHECK: call {{.*}}(i32 [[LOAD]])
+; CHECK-NOT: extractvalue
+; CHECK: ret i32 [[LOAD]]
+define i32 @extract2gep({i32, i32}* %pair, i32* %P) {
+ ; The load + extractvalue should be converted
+ ; to an inbounds gep + smaller load.
+ ; The new load should be in the same spot as the old load.
+ %L = load {i32, i32}* %pair
+ store i32 0, i32* %P
+ br label %loop
+
+loop:
+ %E = extractvalue {i32, i32} %L, 1
+ %C = call i32 @baz(i32 %E)
+ store i32 %C, i32* %P
+ %cond = icmp eq i32 %C, 0
+ br i1 %cond, label %end, label %loop
+
+end:
+ ret i32 %E
+}
+
+; CHECK: define i32 @doubleextract2gep
+; CHECK-NEXT: [[GEP:%[a-z0-9]+]] = getelementptr inbounds {{.*}}* %arg, i32 0, i32 1, i32 1
+; CHECK-NEXT: [[LOAD:%[A-Za-z0-9]+]] = load i32* [[GEP]]
+; CHECK-NEXT: ret i32 [[LOAD]]
+define i32 @doubleextract2gep({i32, {i32, i32}}* %arg) {
+ ; The load + extractvalues should be converted
+ ; to a 3-index inbounds gep + smaller load.
+ %L = load {i32, {i32, i32}}* %arg
+ %E1 = extractvalue {i32, {i32, i32}} %L, 1
+ %E2 = extractvalue {i32, i32} %E1, 1
+ ret i32 %E2
+}
+
+; CHECK: define i32 @nogep-multiuse
+; CHECK-NEXT: load {{.*}} %pair
+; CHECK-NEXT: extractvalue
+; CHECK-NEXT: extractvalue
+; CHECK-NEXT: add
+; CHECK-NEXT: ret
+define i32 @nogep-multiuse({i32, i32}* %pair) {
+ ; The load should be left unchanged since both parts are needed.
+ %L = volatile load {i32, i32}* %pair
+ %LHS = extractvalue {i32, i32} %L, 0
+ %RHS = extractvalue {i32, i32} %L, 1
+ %R = add i32 %LHS, %RHS
+ ret i32 %R
+}
+
+; CHECK: define i32 @nogep-volatile
+; CHECK-NEXT: volatile load {{.*}} %pair
+; CHECK-NEXT: extractvalue
+; CHECK-NEXT: ret
+define i32 @nogep-volatile({i32, i32}* %pair) {
+ ; The volatile load should be left unchanged.
+ %L = volatile load {i32, i32}* %pair
+ %E = extractvalue {i32, i32} %L, 1
+ ret i32 %E
+}
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